Hi all,
I want to try the I2C of the LPC845 BRK following what reported in the user manual
This is the initialization function of the I2C0 in the LPC845brk
And this is the send data function
I tried to launch a program with these two function called but I am doing something wrong.
While debugging the code is stuck here
and the i2c0 registers tell that the i2c is with communication in progress but i tried to see the SCL and SDA lines with the oscilloscopes and I do not see anything passing (always at 3v3). The MSTDAT register has the correct devaddr that I am passing
Can you tell me what I am doing wrongly?
Thanks
Hi @VaneB I think I have made almost everything you mentioned below (you can check it in my first post)
- Provide main_clk as function clock to I2C0
SYSCON->FCLKSEL[5]=0x0; // i2c clock selection: main clock
- Enable bus clocks to I2C0 and SWM
SYSCON->SYSAHBCLKCTRL0|=(1<<5); /* enable clock to I2C0 */
- Configure the SWM
SYSCON->SYSAHBCLKCTRL0|=(1<<7); // Enable SWM clock
SWM0->PINENABLE0&=~(1<<12); /* connect I2C0_SDA to PIO0_11 */
SWM0->PINENABLE0&=~(1<<13); /* connect I2C0_SCL to PIO0_10 */
SYSCON->SYSAHBCLKCTRL0&=~(1<<7); /* disable clock to SWM */
- Give I2C0 a reset
SYSCON->PRESETCTRL0&=~(1<<5);
SYSCON->PRESETCTRL0|=(1<<5); /* reset I2C0 */
- Configure the I2C0 clock divider
I2C0->CLKDIV=500;
- Configure the I2C0 CFG register
I2C0->CFG=(1<<0); /* master mode */
- Enable the I2C0 slave pending interrupt
I am not sure about this. Why do I need a slave pending interrupt? I would like to do it in polling mode: when the MSTpending bit is 1 I write to the MSTDAT register.
This is the basic function that I would like to call in my main()
void i2c0_send_data(uint8_t devaddr,uint8_t value){
I2C0->MSTDAT=(devaddr<<1); // send address with R/W bit =0
I2C0->MSTCTL|=(1<<1); // send start
while(!(I2C0->STAT & 1)); /* wait for i2c0 idle or pending*/
I2C0->MSTDAT= value;
I2C0->MSTCTL=(1<<0); // send continue
while(!(I2C0->STAT & 1)); /* wait for i2c0 idle or pending*/
I2C0->MSTCTL|=(1<<2); // send stop
}
As I said before what I do not see working is this highlighted
At first, I doublechecked that the connections are good and probed the lines directly at the lpc pins but the oscilloscope shows that the i2c lines are always high.
Therefore I tried to do something more direct like this
while(1){
I2C0->MSTDAT=(14<<1); // send address with R/W bit =0
I2C0->MSTCTL|=(1<<1); // send start
}
I keep seeing the SCL and SDA lines stucked at 3v3 eventhough the start bit is set.
Therefore I tried to unplug and plug again the SDA pull-up external 2k2 resistor (i am using the LPC845brk on a breadboard) while the while loop was running and the SCL and SDA lines started sending the address. Indeed what I did was to force a start condition. So in my opinion there should be something that hinders having the start condition of the i2c (lpc does not put sda low) but I am not able to figure out what.
Do you have any idea that can help me?
Hi @VaneB
I am trying to use the attached code bundle
Can you tell me how to import the code bundle in the MCUxpresso?
I am having this issue maybe related to the compiler or to how I imported the project in my folder
After that what shall I do to use test the I2C? I have seen that the I2C folder misses some files that are in the common folder
Thanks
Best regards
