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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