Posted on May 17, 2015 at 21:28I've been trying to work out how to make the STM8S act as an I2C slave and to be honest I'm failing. I think I've set everything up according to the reference manual but for some reason I'm not getting the expected interrupts being fired.
I have a Netduino setup as an I2C master. The logic analyser and the scope both show a write and an address of 0x02 and a NAK being generated on the I2C bus.
I was expecting the STM8S to generate an ACK and an interrupt to request data or to send data. At the very least I was expecting an interrupt to be generated.
I know the interrupt handler is being wired up as I get an error interrupt when I recompile the Netduino code and it redeploys. At this time it messes up the I2C bus.
The STM8S application code is:
#include <iostm8s103f3.h>
#include <intrinsics.h>
//
// I2C interrupts all share the same handler.
//
#pragma vector = I2C_RXNE_vector
__interrupt void I2C_IRQHandler()
{
if (I2C_SR1_RXNE)
{
unsigned char data;
data = I2C_DR;
}
if (I2C_SR1_TXE)
{
I2C_DR = 0xaa; // Some dummy data to send.
}
}
//
// Setup the system clock.
//
void InitialiseSystemClock()
{
CLK_ICKR = 0; // Reset the Internal Clock Register.
CLK_ICKR_HSIEN = 1; // Enable the HSI.
CLK_ECKR = 0; // Disable the external clock.
while (CLK_ICKR_HSIRDY == 0); // Wait for the HSI to be ready for use.
CLK_CKDIVR = 0; // Ensure the clocks are running at full speed.
CLK_PCKENR1 = 0xff; // Enable all peripheral clocks.
CLK_PCKENR2 = 0xff; // Ditto.
CLK_CCOR = 0; // Turn off CCO.
CLK_HSITRIMR = 0; // Turn off any HSIU trimming.
CLK_SWIMCCR = 0; // Set SWIM to run at clock / 2.
CLK_SWR = 0xe1; // Use HSI as the clock source.
CLK_SWCR = 0; // Reset the clock switch control register.
CLK_SWCR_SWEN = 1; // Enable switching.
while (CLK_SWCR_SWBSY != 0); // Pause while the clock switch is busy.
}
//
// Setup I2C.
//
void InitialiseI2C()
{
I2C_CR1_PE = 0; // Diable I2C before configuration starts.
//
// Setup the clock information.
//
I2C_FREQR = 16; // Set the internal clock frequency (MHz).
I2C_CCRH_F_S = 0; // I2C running is standard mode.
I2C_CCRL = 0xa0; // SCL clock speed is 50 KHz.
I2C_CCRH_CCR = 0x00;
//
// Set the address of this device.
//
I2C_OARL_ADD = 0x02; // Seven bit address.
I2C_CR1_ENGC = 1; // Enable the general call address.
I2C_OARH_ADDMODE = 0; // 7 bit address mode.
I2C_OARH_ADDCONF = 1; // Docs say this must always be 1.
//
// Setup the bus characteristics.
//
I2C_CR2_ACK = 1;
I2C_TRISER = 17;
//
// Turn on the interrupts.
//
I2C_ITR_ITBUFEN = 1; // Buffer interrupt enabled.
I2C_ITR_ITEVTEN = 1; // Event interrupt enabled.
I2C_ITR_ITERREN = 1;
//
// Configuration complete so turn the peripheral on.
//
I2C_CR1_PE = 1;
}
int main()
{
__disable_interrupt();
InitialiseSystemClock();
InitialiseI2C();
__enable_interrupt();
while (1)
{
__wait_for_interrupt();
}
}
Can anyone see where I'm going wrong?
Regards,
Markl
