I2c Read Write

•If the bit is 1 the master is reading from the slave. The TWWC bit is set when attempting to write to the TWI Data Register - TWDR when TWINT is low. Read serial data from an I2C slave. DS3231 is a low-cost, accurate I2C real-time clock (RTC), with an integrated temperature-compensated crystal oscillator (TCXO) and crystal. Here is some example code for a Microchip 12F1822 microcontroller which is setup as an I2C Master to communicate with one of our Servo*Pro chips (which is an I2C slave). The text of the Arduino reference is licensed under a Creative Commons Attribution-ShareAlike 3. Read a number from the device at a 7-bit I2C address as a 16-bit number. I am trying to interface PIC18F24K40 with DS1307. The 16, big-endian, and integer chosen for the format. We’ll show you how to wire the display, install the library and try sample code to write text on the LCD: static text, and scroll long messages. READ + Register. endTransmission () In master mode, this ends the transmission and causes all buffered data to be sent. Thanks in Advance. This is tested working with an i2c sensor. Communication(Write to & Read from) is always initiated by a Master. write (data, timeout=-1) ¶ data is written. In our case, we wanted to write to the configuration register and thus the address was simply left shifted by one leaving the LSB zero. Software For each I2C device on the bus you must create an object of the class I2CEngine. Number of I²C modules per MCU differs from chip to chip. so now lets say i want to write the number 65 to adress location 2 (do i need 10ms pauses in between all these i2cwbyte. The I2C protocol is a very useful serial communication protocol. let inValue = pins. The last bit of the control byte is read/write bits, this bit is zero for the write operation and one for the read operation. The format for this command is as follows:. (Note: the -r flag may interfere with write-only devices, but the default probing method does not work on the Beagle. Standard I2C devices operate up to 100Kbps, while fast-mode devices operate at up to 400Kbps. The low current consumption of 2. Here, we use three DHT22 sensors on a single I2C interface. Can any one give me his codes for refrance regarding how to READ and WRITE to 24C04. The test_read_data() function calls the i2c_eeprom_read_data(), which reads data from I2C EEPROM to memory position of given pointer. To know when the transfer is complete, the application may monitor the state of the CPAL_State field or use the DMA Tx/Rx Transfer Complete interrupts when DMA mode is enabled. This application note demonstrates how to use the EFM32 I2C module to talk to an I2C temperature sensor. Pete Bratach November 05, 2018 20:22. Values will be displayed on the 16x2 LCD connected to each of the Arduino. Hi I wanted to do a i2c read - write operation on imx6. Writes a 1-byte offset value, pauses, then reads an 8 character string from the slave. Connection is easy:. The ADXL345 is a complete 3-axis acceleration measurement system with a selectable measurement range of ±2 g, ±4 g, ±8 g, or ±16 g. i2cReadNumber(32, NumberFormat. Have you configured your Arduino to run as an I2C slave? You will need a couple things: 1)An address for the Arduino (you can choose one, just make one up 0xA1 or what you want) 2)A register scheme to store data for both writing to and dumping from. register import Register controls. This task must be triggered before the last byte is extracted from RXD to ensure that the TWI master sends a NACK back to the slave before generating the stop condition. If stop is true then a STOP condition is generated at the end of the transfer. Each I2C device is assigned a unique address that's used to identify it during read and write operations. This is the code for Arduino as an I2C slave. There are three I2C busses (I2C0, I2C1, I2C2), of which I2C2 is easily usable (Expansion. lease_get_mtime (C function) lirc-read (C function) lirc-write (C function) lirc_fh (C type) LIRC_GET_FEATURES (C function) LIRC_GET_MAX_TIMEOUT (C function) LIRC_GET_MIN_TIMEOUT. Standard Bus Operations. SSPBUF is the buffer register to which data bytes are written to or read from. • Bit 2 – TWEN: TWI Enable Bit. eeprog is a Linux C program that allows you to read and write to 24Cxx EEPROM. def i2c_rdwr(self, *i2c_msgs): """ Combine a series of i2c read and write operations in a single transaction (with repeted start bits but no stop bits in between). This command will read one byte from the i2c device located at i2c (address). I want to write an Arduino program that simply recieves a string (via the I2C wire library) from a master Arduino, then waits for a request, and sends that string back. Often so have we all implemented an I2C connection. In the normal configuration there is one master addressing several slaves (up to ~100). We all know it's main parts - 2 wires, multiple slaves, sometimes multiple masters, up to 5MHz of speed. !! I don't know why. Bytes read count (Positive number) Specify number of bytes to read from I2C in a transaction. Program a PIC chip as an I2C slave device for custom sensor and I/O interfacing. I wanted to write a c-code to do the same, but i don't know how to address the slave correctly. All addresses for read/write requests sent to I2C devices must be left hand aligned thus allowing the right most bit or LSB free to be used as a directional identifier. I have found a few good tutorials on how to send and receive data via I2C in connected arduinos. I ported my old for F4 to HAL based libraries for F0/F4/F7 series. write(0x40, 0xF3) print bus. A single message writes to the EEPROM. WriteRead would seem to be the answer. This details an SPI to I2C bridge component for use with single master I2C buses, written in VHDL for CPLDs and FPGAs. */ extern s32 i2c_smbus_read_byte (const struct i2c_client * client); extern s32 i2c_smbus_write_byte (const struct i2c_client * client, u8 value); extern s32 i2c_smbus_read_byte_data (const struct i2c_client * client, u8 command); extern s32 i2c_smbus_write_byte_data (const struct. Now we will see 8051 I2C Interfacing Tutorial. Azure Sphere supports several options for performing read and write operations with I2C. This means sending the I2C address with the R/W bit set to write and then sending some additional data like register address. I read 7 bytes of info from an IC into an 8 byte array. Tools to read i2c registers, useful to debug i2c-hid devices in user space - bentiss/i2c-read-register. I tried it several times with this basic code and some minor changes, so hopefully someone could help me out. My timing matches that shown in the datasheet. After some email for I2C library for HAL, I've made it. I guess ASF should handle making the pins output/input as needed by I2C. static int write_bus (int busfd, unsigned char *buf,. 0, and Figure 5-1. Send the START bit (S). This popular system is used in a huge range of chips - just a few examples from this site include the DS1307 (RTC), SSD1306 (OLED Display), DS23017. The CMSIS-Driver API is designed to be generic and independent of a specific RTOS, making it reusable across a wide range of supported microcontroller devices. application note AN3281 bundeled with; the related source code package STSW-STM8004; Downloading from the ST website requires a (free) registration. Here is an example. The Master must specify which device it wants to read or write from before any data can be transferred. Using STM32 DMA and I2C to read data from MPU6050 - Updated 09 June 2014 on stm32 mpu6050 dma , stm32 i2c dma , mpu6050 reading In the previous post , an example of using STM32 DMA to perform a simple data copy between 2 arrays was introduced. STM32F0 I2C - Tutorial 7 with STM32CubeMX. I realized i would write the 8 bits ( vendor bits(4),adress(3), and read/write bit) which is what alenze said. I2C_MSG_RESTART¶ RESTART I2C transaction for this message. The library uses the 7bit addresses. i2c Multiple Byte read and write c++. write (data) Send data. exe, but run under OLD MS-DOS environment and written in Assembly(MASM-6. The write operation used here to the AT24C02 is Byte Write. At least, I used that for a quick hack, and just followed the examples in the doc, believe it or not, here:. If you're really curious about the nitty-gritty internal details of I2C and SPI, you might want to read the source code of Wiring Pi, which you can clone from here. PCF8574 is a I2C chip which can expand IO up to 8 and the initial state of IO is HIGH. Here one Arduino will act as Master and another one will act as Slave. The second way to read data using I2C is using the Write/Read Function. The write function takes 3 arguments: slave_address, pointer to an array and length of the array. 2, the smbus2 library also has support for combined read and write transactions. Control PCF8574 IO using i2c-tools. Because the aim is the non-blocking communication, the CPU will not wait until each byte is transferred, but the algorithm allows the application to continue the execution. Serial to I2C Conversion makes it easy to talk to I2C devices using NCD standardized commands. S 41 01 P (adaptor replies with "FE") If we are using the I2C Keyboard, then the LED and switch are both connected to the same pin. lease_get_mtime (C function) lirc-read (C function) lirc-write (C function) lirc_fh (C type) LIRC_GET_FEATURES (C function) LIRC_GET_MAX_TIMEOUT (C function) LIRC_GET_MIN_TIMEOUT. If you use Wire. e write state) Master as receiver requires data from slave-transmitter(RW=1 i. Since it’s also a licensed trademark, some vendors use another name (such as “Two-Wire Interface”, TWI) for the same bus. Will send out read byte commands on the /dev/i2c-2 line to probe for addresses, and return any devices found. Read a number from the device at a 7-bit I2C address as a 16-bit number. I2C chip devices usually monitor a number of different physical devices on a motherboard, such as the different fan speeds, temperature values and voltages. This initialises the I2C system with your given device identifier. This command sends the message exactly as embedded in the command to the addressed slave I2C device. I am having problems communicating via I2C with the video product. A general I2C/TWI bus topology with multiple masters and multiple slaves connected to the bus at the same time is shown below: Let us go through I2C protocol basics first. read() from the library are used for EEPROM writing and reading respectively. This parameter appears only when you clear Enable register access parameter. Values will be displayed on the 16x2 LCD connected to each of the Arduino. Without a pull-up resistor, the bus will only read '0'. This must be written (an I2C write cycle) before data can be read or written. Case closed! PS - I will post the ported SoftI2CLibrary with @peekay123 ’s help sometime soon. I2C Logic pins: WP - Write Protect pin. This application note demonstrates how to use the EFM32 I2C module to talk to an I2C temperature sensor. master wishes to write to (1) or read from (0) the slave. This part of the FT232H application will read them over I2C, and write them back. Connection and use is quite simple:. write(0x40, 0xF3) print bus. Because the eeprom is using an internally address counter, who will be set with a dummy write (it's calling random read). DS3231 is a low-cost, extremely accurate I2C real-time clock (RTC) with an integrated temperature-compensated crystal oscillator (TCXO) and crystal. To select the desired I²C module, simply change the letter x in the routine prototype for a number from 1 to 3. This lets us make continuous reads of the axis data. Attiny45 I2C DS1307 ReadOnly; Attiny45 I2C DS1307 read and set time; ATtiny45 PCF8574 LCD DS1307 Show Time Only by TinyWireM. Here is the code I have so far: #include <stdio. However, I don't see a way of telling the I2cDevice to write on the general call address and read (or write) on the slave address after a restart. 1 Address maps The PCF8574 and PCF8574A are functionally the same, but have a different fixed portion (A6 to A3) of the slave address. Basically you can only call Wire. When CPAL_I2C_Read() or CPAL_I2C_Write() function is called, the user application may perform other tasks while the transfer is ongoing. This initialises the I2C system with your given device identifier. Writes a 1-byte offset value, pauses, then reads an 8 character string from the slave. start bit, address, data, stop). Instead of sending the stop condition it is also allowed to send another start condition again followed by an address (and of course including a read. The struct i2c_driver structure describes a I2C chip driver. I will reply as soon as possible. void I2C_Write(unsigned data) {I2C_Hold(); //Hold the program is I2C is busy SSPBUF = data; //pg82/234} unsigned short I2C_Read() The final function that we have to know about is the I2C_Read function. Operating at 115. TCG TPM I2C Interface. For more info about used EEPROM AT24C01A, see attached datasheet. DS3231 is a low-cost, accurate I2C real-time clock (RTC), with an integrated temperature-compensated crystal oscillator (TCXO) and crystal. you should wait for ARDY before you re-program any of the I2C registers (e. It is controlled by external device over UART and/or I2C bus with simple protocols defined in this sheet. Introduction. Schemat do daewoo DTH-29U7K-100D. The write operation used here to the AT24C02 is Byte Write. 0x28 with a 1 in the MSb place is 0xA8. The waveform shows the address of the i2c device is first, followed by one byte of data which was read (output from i2c device). To read this, we need to point to the first register 0x28 with a 1 in the MSb place so the data can all be read at once (auto-increment). vga on bus /dev/i2c-1. so we will Interface EEPROM to check I2C. SM130 is a compact 13. The 8th bit to distinguish between read and write access is added internally with the words i2c. write(0x40, 0xF3) print bus. Connecting a wire between MCU Xtal pads I could energize all circuit but avoid that MCU start and also communicate with serial eeprom. b) Once that code works go back and try to use it with the QZ8920. I2C is a multi-master synchronous serial communication protocol for devices. The test_read_data() function calls the i2c_eeprom_read_data(), which reads data from I2C EEPROM to memory position of given pointer. Thread 4825: Hi,I have come over the problem with LCD. i2cReadNumber(32, NumberFormat. Current address read is in which the internal data word address counter maintains the last read address or last write address incremented by one. If you're really curious about the nitty-gritty internal details of I2C and SPI, you might want to read the source code of Wiring Pi, which you can clone from here. COM] says: When you perform any operation, apart from a MOV on a register the PIC {or SX } first reads the register, then it performs the operation on the number it has just read and finally it write the number back to the register. I2C read and write operation Dear all, I am using MPLAB X ide. Currently, the other microcontroller is sending a write-read command to an i2c device request an address. Expect/Send acknowledge bit (A). July 19, 2019. The 16, big-endian, and integer chosen for the format. Using freeipmi,. The Random Read reads only a single byte on a random position specified by the start address. the address is composed of 7 bits and most often most of these 7 bits are set in factory. To start TWI interface write one to this bit. A 7-bit address omits the read/write bit. I have used MCC configuration for i2c interface. State = 1 indicates last IN Report. Opis procesora VCT49xyI firmy Micronas bez napisu "WORK IN PROGRESS" nr: 6251-573-1AI w pliku pdf z 2003 12 12 zawiera 374 strony. Code samples in the reference are released into the public domain. protocol) as it makes it possible to use the device driver on both SMBus adapters and I2C adapters. Reading Data. This is the simplest way to perform operations on an. import smbus I2C_ADDRESS = 0x20 bus = smbus. Here one Arduino will act as Master and another one will act as Slave. If you plan on using the pins from user space, then you may want to add a udev rule to help. addr) Send only the read / write bit. Hello folks, it's time for I2C! Currently, related to Serial Communication, maxEmbedded features RS232 and SPI communication. To read this, we need to point to the first register 0x28 with a 1 in the MSb place so the data can all be read at once (auto-increment). Typically I find there are four wires needed to connect the Raspberry Pi to an I2C device – one for power (usually 3. The I2C protocol is a very useful serial communication protocol. I trying to read and write an Atmel 24C256 EEPROM with a Raspberry Pi B+ over I2C, but I'm having trouble getting it all to work right. Attached is my example, what I'm using for I2C communication. Write data to IO. Please refer to the reference manual, details on I2C clock generation, for max allowed theoretical frequencies for different modes. Here is the code:. In the example, 0x40 is the correct address for the sensor on i2c and 0xF3 is the command for "no hold" measurement of temperature. When the master (microcontroller) wishes to talk to a slave device (for example ADC), it begins communication by issuing a start condition on the I2C bus, and then issues a stop condition. read() from the library are used for EEPROM writing and reading respectively. The FM24W256 is capable of supporting 1014 read/write cycles, or 100 million times more write cycles than EEPROM. You are required to register before you can post: click the sign-up link above to proceed. If more than 54 bytes were read, then more IN Reports (each 60 + 5 bytes) may be received. The latest version is v1. I read 7 bytes of info from an IC into an 8 byte array. Note that the LSB indicates whether the operation is a read or write. Articles posted in the Keil forum are visible immediately for everyone to read and respond. Now we read the data by sending a write to the device 0x50, send the address to read from 0x00, send a read to the device 0x50 and we receive the data which reads as 0xAA (170). eeprog is a Linux C program that allows you to read and write to 24Cxx EEPROM. I have used MCC configuration for i2c interface. This application note demonstrates how to use the EFM32 I2C module to talk to an I2C temperature sensor. Zawiera opis s. Write Protect (WP) Pin number 7 of 24LC512 is a hardware Write Protect input. Starting with v0. Load SPI and I2C modules and set /dev/ permissions to enable read/write by the user running the gpio program. Each message has an address frame that contains the binary address of the slave, and one or more data frames that contain the data being transmitted. In such cases it must first write to the slave device, change the data transfer direction and then read the device. Current address read is in which the internal data word address counter maintains the last read address or last write address incremented by one. Write data to an I2C device on the Arduino hardware. Once the device address with the last bit set is sent, the device will clock out the data in the current data word address. which will not read back the data that has been written (and the compare will fail). I follower the available documentation in ROCm, and in Linux. As you can see, this memory type is defined as read-only. A register read is accomplished by first sending the standard I2C write header, followed by the two register bytes corresponding to the data to be read. Since it's also a licensed trademark, some vendors use another name (such as "Two-Wire Interface", TWI) for the same bus. */ void RTC_SetTime. The next three bits of the control byte are the chip select bits (A2, A1, A0). Secondly, after reading the documentation I still don't know how to discern the difference between READ and WRITE addresses in an I2C slave interrupt, so that I can act on a command OR send data back in necessary. The Raspberry Pi's I2C pins are an extremely useful way to talk to many different types of external peripheral; from the MCP23017 digital IO expander, to a connected ATmega. I'm using two I²C examples provided from TI msp430g2xx3_uscib0_i2c_04 (single read) and msp430g2xx3_uscib0_i2c_06 (single write). I2C is a protocol for communication between devices. This should get us comfortable with the idea of using EEPROM and also give us a feeling for how much data can really fit on a small device. Load SPI and I2C modules and set /dev/ permissions to enable read/write by the user running the gpio program. The 'x' is the extra Read/Write bit to complete the other 7 address bits (making 1 byte) which we set depending on whether we want to read or write (for help understanding hexadecimal numbers, check out our Numbers in Hex, Binary, and Decimal article. Standard Bus Operations. Because the aim is the non-blocking communication, the CPU will not wait until each byte is transferred, but the algorithm allows the application to continue the execution. Hi I wanted to do a i2c read - write operation on imx6. They are extracted from open source Python projects. This example works with LED drivers and PGA's, but not with eeprom's. The methods takes care of the I2C Control byte. Can any one give me his codes for refrance regarding how to READ and WRITE to 24C04. This is particularly true if setting mode to cp (write byte/read byte with PEC). It can only be used as a Master on the I2C bus, and it cannot be used as a Slave. Read serial data from an I2C slave. Andy I think your code writes a buffer of data and reads a buffer of data but doesn't control the EEPROM's internal address. LCD C code can contact me by posting his/her email on this thread. When the master wants to communicate with slave then he asserts a start bit followed by the slave address with read/write bit. write from file. The chip select size is 3 bits (A2, A1, A0) it allows the user to connect maximum 8 devices to the I2c bus. file_read, I2C_SLAVE, addr) fcntl. n and then read back from the address n+1, n+2, n+3 etc. An I2C slave cannot write to a master, only a master can read and write to a slave. de) The Shiny New I2C Slave Framework 6. For more information on I2C communication, refer to Support I2C Communication and The Raspberry Pi I2C Interface (MATLAB Support Package for Raspberry Pi Hardware). read (n, timeout=-1) ¶ Returns a sequence of n bytes. This starts the clock running so the data on MISO is brought into the uC. //notice you will lose the data in flash if you erase all flash when you download new code from computer. The I2c send commands seem to work alright, but when I want to receive i have to do the following: send startcondition+write->send the byteaddress to read-> send repeated start+no_read -> receive byte from the sensor -> stop or read another byte. PCF8574 is a I2C chip which can expand IO up to 8 and the initial state of IO is HIGH. Using freeipmi,. Configure I2C master block for Write format Configure I2C master block for Read format. ) i2cget and i2cset write and read to devices. Thanks in Advance. Programming and reading I2C memory devices is a common use case for the Aardvark I2C/SPI Host Adapter. This part of the FT232H application will read them over I2C, and write them back. This is called dummy write. For the Random and Sequentially Read this function performs a Write to specify the Start address to read from and a Read to read the data from this address. IO_IOCTL_I2C_SET_RX_REQUEST Set number of bytes to read before stop. 11) Now they work on Intel ICH-x series Chipsets. Then I read specs again, for I2C memory, and notice that 16 bit addressing is not the way to work with this memory type. There is actually an extra element at the end of the string '\0', you can read it and print it but it'll come up as a block or something. #include #include #include #include "i2c. We can check for any devices on the I2C bus using the command in a Terminal window:. write() and EEPROM. ) i2cget and i2cset write and read to devices. I want to use arduino to simulate an I2C device with another microcontroller. All of the I2C addresses I've seen are seven bits (for eight bit addressing). add ("REGISTER_NAME", 0x00, Registers. Master Write/Read to/from FRU PROM. I2C bus is a Byte Oriented bus. If stop is true then a STOP condition is generated at the end of the transfer. Before moving on, consider reading their good data sheet. Hi, i am trying to write an application emulating a I2C EEPROM (two byte addresses). Learn the basic principles behind I2C serial communication, including signaling waveforms, terminology, and related configuration of the "I2C" Express VI. I'm using two I²C examples provided from TI msp430g2xx3_uscib0_i2c_04 (single read) and msp430g2xx3_uscib0_i2c_06 (single write). For every conversion one must again write the configuration register. Send the slave address (ADDR). Each message has an address frame that contains the binary address of the slave, and one or more data frames that contain the data being transmitted. Currently, the other microcontroller is sending a write-read command to an i2c device request an address. Communication(Write to & Read from) is always initiated by a Master. If this bit is set during master transmit mode, it indicates that a write to SSPBUF register was attempted when I2C conditions was not valid for a transmission to be started. This command will read one byte from the i2c device located at i2c (address). It's good I send a read command to the slave, I receive only the first byte (value = 05) all other byte = 0xff. 5 A (typical, static) is great for mobile applications and the latched output ports directly drive LEDs. After having sent the address byte (address and read/write bit) the master may send any number of bytes followed by a stop condition. There are several ways to do this with the Aardvark adapter, including using Control Center, Flash Center, or the Aardvark API. read_byte(0x40) print bus. DS3231 is a low-cost, accurate I2C real-time clock (RTC), with an integrated temperature-compensated crystal oscillator (TCXO) and crystal. I2C EEPROM Interfacing with STM32F4 Discovery. For additional information take a look at the I2C/SPI activity board user's manual. endTransmission () In master mode, this ends the transmission and causes all buffered data to be sent. If you are not familiarized with I2C protocol, read my article on Inter-Integrated Circuit communication. The way the I²C bus works is a 7-bit address is passed along with a read/write bit that tells the chip if it should write the incoming data or read it and send it back. need i2c read/write in linux c? Hi this is SrikanthPilli, i was struggling with i2c write/read operation. The I2C communication begins by initiating a start condition. It is provided as example code; if you want a real program use i2cget from the i2c-tools package. This is useful for checking what devices are functioning properly. I’m trying to setup communication between an STM32F103RET6 and a MPU-9150 over I2C. This is a very popular protocol that can be used to address a large number of slave devices that are connected to the same bus. I2C bus is a Byte Oriented bus. In this column, the author takes the reader through the process of writing I2C clients in Linux. VGA out can often support I2C directly so no need for any external devices. my mistake is using adress (0x53 is true) I read wrong it,but now problem is HAL_I2C_Mem_Read(&hi2c1,ADXL345_I2C_Adress1,DATAXL_INC,I2C_MEMADD_SIZE_8BIT,out,2,1000); I want to get all angles at the same time with multiple bytes read , is it true to use DATAXL_INC. Welcome to the homepage of RW utility. A device responds if it pulls the SDA line low after its address (including a read bit) is sent on the bus. If R/W is equal to zero, then it is write mode. This brute force method is a fast and easy way to see if any chips are responding, and to uncover undocumented access addresses. i2c_rdwr (*i2c_msgs) ¶ Combine a series of i2c read and write operations in a single transaction (with repeated start bits but no stop bits in between). The I2C pins include a fixed 1. Connection is easy:. DS3231 is a low-cost, accurate I2C real-time clock (RTC), with an integrated temperature-compensated crystal oscillator (TCXO) and crystal. My referensers like “ARD2. An i2c context represents a master on an i2c bus and that context can communicate to multiple i2c slaves by configuring the address. This section describes the algorithms for the multi-byte read and write I2C messages. long write_byte(int addr,char val). import smbus I2C_ADDRESS = 0x20 bus = smbus. I'm using two I²C examples provided from TI msp430g2xx3_uscib0_i2c_04 (single read) and msp430g2xx3_uscib0_i2c_06 (single write). The GPIO works fine but the I2C bus cannot be accessed for two reasons: 1. In any event if $1D is hex 1D, then this is a very stange address. It is useful when the same i2c object is used by multiple threads to. To read data from the slave, do. The slave address used should only be the top seven bits. The purpose of this 'write' operation is to adjust the value in the configuration register of the HMC5883L to tell it to be in continuous operation mode. You'll just read and write bytes here and there as needed. The master always initiates transactions. The format for this command is as follows:. I2C: PMUXs 2 2. Read a number from the device at a 7-bit I2C address as a 16-bit number. write some data and then read from the slave with a repeated start and no stop bit between. The following code will read a byte from position 0x10, of the register at 0x3f of the device /dev/i2c-2. The Saleae software includes a protocol analyzer for the I2C protocol. An additional bit of the address determines if the operation is a write to the chip (0), or a read from the chip (1). In every i2c device data sheet you wil find a section detailing how to address your device in either write or read mode. In this example, 32 bytes are read at a time. /eeprog -f -i 2c02. Master mode is used. With the old example I'm able to read and write (so no hardware fault) successful.