Hmm, well update - I figured out that I was missing the following line:
rcc_periph_clock_enable(RCC_GPIOB);
before my GPIO setup calls. Makes sense. The thing I'm confused about now
is the clock speed. With i2c_set_fast_mode(), I get a clock speed of 178
kHz. With i2c_set_standard_mode(), it's 266 kHz. Weird, shouldn't fast mode
be.. faster?
Also, one more thing: if I try and wait for "address transferred" by doing:
while (!(I2C_SR1(I2C1) & I2C_SR1_ADDR));
after the i2c_send_7bit_address() call, then it gets stuck here. So I think
I am still doing something wrong with the setup.
On Sat, Aug 1, 2020 at 6:00 PM Chris Chronopoulos <
chronopoulos.ch...@gmail.com> wrote:
> I've also noticed that if I put in the while-loops to check for status
> register updates, e.g.
>
> while (!((I2C_SR1(I2C1) & I2C_SR1_SB)
> & (I2C_SR2(I2C1) & (I2C_SR2_MSL | I2C_SR2_BUSY))));
>
> Then this just gets stuck, confirming that the start condition is not
> being sent.
>
> On Sat, Aug 1, 2020 at 5:52 PM Chris Chronopoulos <
> chronopoulos.ch...@gmail.com> wrote:
>
>> Hi, just joined this list, not sure what the protocol is.. but I have a
>> question about getting I2C working on the STM32L1(52RE).
>>
>> First of all, I see that there are two versions of the I2C API: v1 and
>> v2. Can someone explain what the difference is between these? From digging
>> through the library, I can see that different device families use different
>> versions, e.g.:
>>
>> F0: v2
>> F1: v1
>> F2: v1
>> F3: v2
>> F4: v1
>> F7: v2
>> L0: v2
>> L1: v1
>> L4: v2
>>
>> So when following code examples, I guess I need to find examples that use
>> the v1 API. In libopencm3-examples, the only STM32 I2C v1 example I could
>> find is this one for F1
>> <https://github.com/libopencm3/libopencm3-examples/tree/master/examples/stm32/f1/other/i2c_stts75_sensor>.
>> Unfortunately, the i2c_setup() function in this code doesn't compile for
>> L1, because of some differences between the RCC and GPIO API's (namely,
>> RCC_AFIO and gpio_set_mode() are not defined for L1). So I made some
>> adjustments based on my best guesses, and ended up with this code
>> <https://gist.github.com/chronopoulos/d34de9b6119d4ec052451d6afaa99e79>,
>> which compiles. But, when I monitor the I2C lines with a logic analyzer, I
>> see nothing. Dead silence.
>>
>> Am I missing something? Can anyone provide an example of I2C being used
>> on STM32L1?
>>
>>
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