Pic i2c software slave

The addition of a clock line makes reception timing much more easier and thus reduces transmission errors. The standard i2c library for the arduino is the wire library. Data can flow in any direction on the i2c bus, but when it flows is controlled by the master device. The mikroc pro for pic provides routines for implementing software i.

Pic mcu with ssd6 oled i2c mode example mikroc projects. After setting the pic to be a slave on the i2c bus, clear the flag. In order to use pic18f4550 i2c in slave mode, we must configure sda and scl pins as inputs rc3 and rc4. The only pins you need to wire up, are the io pins you are using.

If this bit is 0, it means that the master wishes to write data to a register of the slave, if this bit is 1, it means that the master wishes to read data from a register of a slave. Therefore, if we use mikroc pro, we do not need to care much about the i2c module internal configuration register of pic microcontrollers. I is a bidirectional protocol i2c is a bidirectional protocol. Most leading mcus comes with at least one dedicated i2c host adaptor built in. Multiple objects for multiple software i2c buses and clockstretching by slave devices are supported. In this section, we will see how pic18f4550 microcontroller i2c module works in slave mode. So you have to wait in software for each command to be completed before issuing the next one. Code for master to slave transfer of one byte with switch debouncing can be found here. The pic, as slave i2c device, will execute the commands i. A timeout feature is included to prevent lockups by faulty or missing hardware. Here each slave must be enabled through the slave select pin in order to communicate with the master. Here, the i variable is incremented and sent to the slave via the i2c bus. I2c i2c overviewoverview l i2c is a bidirectional protocol l data is sent either direction on the serial data line sda by the master or slave.

The clock frequency of the software i2c library is fixed to 20 khz slow. But in terms of speed, spi is still faster due to its pushpull driver compared to the opencollector driver for i2c. This expample uses i2c bus for a master and slave comunication using a pic18f4550 as master and a pic16f877a as slave. Software i2c library for avr mcus extreme electronics. Only the master mode of i 2 c interface is implemented in this application note. When the slave is ready, it releases scl and the master device clocks the data from the slave buffer. An i2c device can operate as either a bus master, bus slave, or both, depending on the. In order for alaudine to be controlled by ethernaude via this i2c bus it was necessary for me to program i2c slave routines in my existing power supply control software which has been running flawlessly for over a year now. I2c pic master to pic slave routine ccs view topic. I2c is a multimaster, multi slave communication protocol. On an i2c bus, one can have more than 1 master and multiple slaves. Ckp bit must be set in software to release the clock and allow the.

Using the pic devices ssp and mssp modules for slave i2c. I2c communication between pics northwestern mechatronics. If you are trying to set up your pic as master of an i2c bus using sw. The microcontroller must function as the master device and multiple masters are not supported. As i previously referred on other posts, the pic 16f690 will now support i2c protocol by hardware for the slave device, meaning that interrupt service routine will be available, serving i2c master whenever necessary without the necessity to pool the i2c bus. Please give me a description of your software development setup, so i will try to get the same tools as you. After that, we will see its driver in mplab xc8 compiler.

It gives you a fully defined protocol for data transfer between multiple devices over two wires. Then, try to use both of your boards with another i2c device. I2c everything you need to know hardware and software. The ft201x would be used where an external microcontroller or fpga needs to transfer data to and from a pc. They can be configured to act as master or slave, and the speed can also be altered. For the master pic, we first need to define the output pins and force hardware i2c communication. When the data is received by the slave, it is moved to the portb register. Program sends data to eeprom data is written at address 2. While this library is sufficient most of the time when you want to communicate with devices, there are situations when it is not applicable. Spi tutorial with pic microcontrollers serial peripheral.

I2c communication with pic microcontroller, eeprom. In this application note, the basics of the i2c slave protocol will be covered. Here is some example code for a microchip 12f1822 microcontroller which is setup as an i2c master to communicate with one of our servopro chips which is an i2c slave. This program also has an interrupt driven i2c handler to manage the i2c from the start event. Program a pic microcontroller as an i2c slave device for. This application note describes the software implementation of i 2 c interface routines for the pic16cxxx family of devices. Master and slave i2c implemented on one pic ccs view topic. Once youre familiar with how the i2c protocol works with pics, you can now use i2c devices like mpu6050 accelerometer or the bmp280 barometric pressure and altitude sensor. But some times we need more than one i2c interface or we need i2c lines on some other io pins than those allotted to the. Stephen bowling microchip technology incorporated using the picmicro ssp for slave i2ctm communication. I2c communication protocol tutorial i2c bus with pic. Spi communication between pics northwestern mechatronics wiki. Pic to pic over i2c default examples matrix user forums. The range of slave addresses will actually address different sections within the 24c16.

The master reads the adc channel 0 and sends the 8bits data to the slaves, and this one shows the data in the lcd display. Before you start, you should be aware that the pic i2c engine cannot queue commands. Sip modules as small, simple pcbs with a single row of io pins along one edge, and our standard i2c connector. These routines are hardware independent and can be used with any mcu. Interface i2c with pic16 microcontroller controllerstech. Usb to i2c example using the ft232h and ft201x devices. Program a pic microcontroller as an i2c slave device for custom. Jul 07, 2019 microchip pic microcontrollers do have a hardware module called mssp which is an acronym for master synchronous serial port. In this excellent article fred describes how to use the i2c master and slave modes for a pinewood derby racing application. Aug 19, 2016 introduction i2c or interintegrated circuit is a pretty neat communications protocol. An734 using the midrange enhanced core pic16 devices mssp. This example uses the ft201x device but the ft200xd device can be used with no software changes. Pic16 spi tutorial simply put, synchronous serial protocols like spi and i2c have a separate line for timing the clk line while asynchronous protocols like uart rs232 doesnt. Mikroc pro for pic provides a builtin library that we can easily use to transfer data to i2cslave devices.

Oct 31, 2019 in software i2c weve to configure the pins used scl and sda by mikroc software i2c library as shown in the help file. The mssp module can be used to implement either i2c or spi communications protocol. This implementation is for a single master communication to multiple slave i 2 c devices. Originally in i2c, slave address was restricted to 7 bits which give 128 unique addresses out of which 16 are reserved. Most microcontrollers now have specialized pins that are devoted to the i2c bus sig n als sda data and scl clock, and the compilers used to program them have instructions or macros that make it easy to control slaves through the bus.

Mcc generated i2c slave code is incrementing data address pointer when it shouldnt. The master i2c device in this example, an arduino uno will issue commands to the slave i2c device by writing to a select location in the memory array. Several of the midrange enhanced core pic16 microcontroller devices have a master synchronous serial port mssp. Once the mssp module has been enabled, it waits for a start condition to occur. This feature allows us to implement an i2c interface such that the chip will function as a slave i2c device. Hello jallum, i need to do work i2c master and slave in the same pic, but when i. In order to write data or read data from the slave, we have to follow particular sequences as given below to write data, do the following. This also will permit slave pic to run other tasks like acquiring data from analogtodigital inputs, control outputs, read inputs, etc, and still server pic slave. Hello, all i can find on the internet are assembler sources that allow the pic to be an i2c master. Using the ssp module for slave i2c communication is, in general, a sequential process that requires the firmware to perform. These software routines allow great cow basic programs to send and receive i2c messages. Serial peripheral interface spi interintegrated circuit i2c full master mode slave mode with general address call. Ive changed the master code and it seems to be ok now, but can someone explain me why the master code and the slave code are not compatible.

This example shows how to implement a software i2c master, including clock stretching. Perhaps best of all, the software heavy lifting has. The master then reads the memory array to retrieve the sensor readings. I2c answers some of the problems of spi including no multimaster mode, no slave flow control and more pins to use. The first 256 bytes are at address 50h, the next 256 at 51h, and so on up to the last 256 at 57h for a total of 2k bytes. Also the configuration should be initialized in the main code always before initializing the display with this line. For the slave pic, we first need to define the output pins, define the name of the device and force hardware i2c communication. If your microcontroller does not have a hardware i2c module then please use the software i2c great cow basic library.

This program uses the hardware i2c module within the microcontroller. This the reason why the slave is only available in hardware mode, not software. No hardware i2c module is required for these routines all communication is handled in software. All i can find on the internet are assembler sources that allow the pic to be an i2c master. Our free realterm software talks directly to the i2c 2pc bl233. The pic 16f628a doesnt support hardware i2c so i had to write my own i2c functions in software. Program a pic microcontroller as an i2c slave device for custom sensor and io interfacing march 03, 2016 by raymond genovese no i2c interface with that sensor. It is written in c for the pic processor, but should be applicable to most. How easy it is to use, how it works and when to use it the i2c protocol is used in a huge range of chips just a few examples from this site include the ds7 rtc, ssd6 oled display, mcp23017 serial expander. Program a pic chip as an i2c slave device for custom sensor and io interfacing. Each slave has its own slave address, this way, only one slave will respond to the data. During an i2c communication, the slave after sending the data requested by the master will send a another bit which is the acknowledgment bit, this bit should also be checked by the master to make sure the communication was successful.

These functions will emulate opencollector outputs on the pic. I2c communication with pic microcontroller pic16f877. The master, on the left, and the slave, on the right, are connected as shown above. You can just talk write and read directly from any new serial bus ic with no programming at all. Here, we use three dht22 sensors on a single i2c interface.

In this i2c tutorial you will learn all about the 2 wire i2c serial protocol. Lately ive been taking advantage of that last advantage. In fact the fastest i2c mode, ultra fast, can reach only up to 5 mhz while some spi busses can reach 50 mhz. So it basically now acts like a little i2c sram, or eeprom if you would handle the operands as persistent. Even if you dont use our adaptors, you can use our well thought out pinout and, compact connector for i2c and spi bus devices. As an example, the basic compiler i use to program pics, melabs picbasic pro. After checking the ackdt bit for acknowledgement it should be enable by setting the acken bit. Introduction i2c or interintegrated circuit is a pretty neat communications protocol. But when you want your pic master to communicate with a pc, you need i2c slave software for the pc. I2c communication with pic microcontroller mplab xc8.

Unlike the mplab xc8 compiler which does not provide builtin routines. The bf bit is cleared by reading the sspbuf register, while bit sspov is cleared through software. The article is available for download in pdf format for a modest fee, and the software related to the i2c slave application in pic ccs c for the pic16f873 is located at the circuit cellar fdtp site for free. C from eeprom and send its value to portb, to check if the cycle was successful see the figure below how to interface 24c02 to pic. My real problem is about the i2c interrupts while reading. This i2c tutorial shows you how the i2c protocol or more correctly written i 2 c sometimes written as iic stands for inter ic communication and is intended for very short distance communication between ics on a single pcb. The first 256 bytes are at address 50h, the next 256 at 51h, and. I have written tutorials about interfacing i2c with stm32 and lpc2148 and today we are going to interface i2c with pic16 microcontroller. I2c inter integrated circuits is a very popular communication protocol.

That is, the last three bits dont matter and the 24c16 really uses all i2c slave addresses 50 through 57 hexadecimal. C communication with pic microcontroller using mssp module. A slave cannot initiate a transfer over the i2c bus, only a master can do that. The i2c slave can be put into a sleep mode by the i2c master writing a nonzero value into the i2c slave buffer location 0, and can wake up. What i would like to do, is to enable an i2c slave to either ack or nack depending on the data received on the i2c. Uses hardware uart rs232 uses hardware mssp i2c boostc implementation of an734a ds00734a i2c slave code written in poll mode and can be converted to isr hardware. Two efm32 i2c modules are connected and set up to both transmit master mode and receive data between each. Jun 03, 2018 multiple objects for multiple software i2c buses and clockstretching by slave devices are supported.

Nov 24, 2011 inter ic communication or i2c is a two wire serial communication bus used to connect a variety of external peripheral with a microcontroller. Ethernaude uses a sx52 fast microcontroller and supplies an i2c bus. This is how the i2c master can turn off the i2c slave s pwm output and. I2c communication between pics northwestern mechatronics wiki. Pic mcu is connected scl, sda pins to 24c02 eeprom. Following the start condition, the eight bits are shifted into the sspsr register.