I want to simulate an I2C slave device using a generic 8051 MPU which doesn't have hardware I2C(not like 80C552). I know it is easy to implement software simulated I2C in master mode, but I want to turn my 8051 MPU to be a slave device. How can?
I have only two microcontroller on the IIC bus. The master is fine I can read and write to external eeprom. However I am using an interrupt to trigger the slave when the master is ready to send data. This triggering is successful, however the data received is DEFINITELY not being sent. I think the problem may be timing between the transmitting and receiving or the my method of receiving the data. Are there any sample code existing for the slave (software) I can look at? Grateful for any help!!!
The other problem with a software implementation of I2C is that the slave is not in control of the clock. The master sets the clock rate. Since the I2C spec says that the bus is supposed to operate at 100 kHz (for the minimum rate), a conforming master can generate this clock even in hardware, and thus the slave software implementation must be able to keep up at 100 kHz. This speed requires a fairly high clock rate for the 8051 just to sample the clock and data pins and accumulate the data in time. (The lower clocks per instruction cycle devices also help.) I2C devices are allowed to operate at slower clock rates, but only when the master is clocking slower than 100 kHz. This is easy when the software implementation is the master. It simply generates whatever clock it wants to or can do. But when you're stuck with an inflexible master that you can't slow down, you have to beef up the bit-banged slave implementation accordingly. And a device marketed as a separate component might be connected to any master.
Are there any sample code existing for the slave (software) I can look at? I know of no slave software that does not use IIC hardware. What keeps you from replacing the chip with one that has IIC hardware? e.g. the Philips P89C66x series are pin compatible with any standard '51 and have IIC hardware. Erik
I am not entirely rigid with the chip. However I have access to two bipom board with atmel 89S53. I will ideally like to be able to utilise thses two board since I already have easy access to connect LCD and keypad which I have already interface. The alternative will be to use SPI however, I am using MicroIDE which doesn't recognised the special function register SPDR,SPCR,SPSR. If any one know how this can be done grateful for any assistance. Or maybe I'll try Keil.
I am not entirely rigid with the chip. However I have access to two bipom board with atmel 89S53. You can replace the 89S53 with a pin compatible P89C66x. The P89C66x is ISP via the serial port, so if the board has a RS232 connection, you will have ISP. Erik