Thanks for this, It's been applied in 4b16af6e Thanks for the clear examples of where the values were wrong. Bright side, it's even smaller code than original buggy code :)
FWIW, it's easier for me to work with patches from github, though
feel welcome to keep sending patches via mail.
Cheers,
Karl P
Filip Moc <d...@moc6.cz> wrote:
> This fixes problems when values such as 512..639 or 1024..1151
> or ... or 32768..32895 are passed to iwdg_set_period_ms.
>
> Signed-off-by: Filip Moc <d...@moc6.cz>
> ---
> lib/stm32/common/iwdg_common_all.c | 54
> +++++++++++++++++++-------------------
> 1 file changed, 27 insertions(+), 27 deletions(-)
>
> diff --git a/lib/stm32/common/iwdg_common_all.c
> b/lib/stm32/common/iwdg_common_all.c index f2b1c1d8..1e299893
> 100644
> --- a/lib/stm32/common/iwdg_common_all.c
> +++ b/lib/stm32/common/iwdg_common_all.c
> @@ -42,6 +42,7 @@ relevant bit is not set, the IWDG timer must be enabled by
> software.
> #define LSI_FREQUENCY 32000
> #define COUNT_LENGTH 12
> #define COUNT_MASK ((1 << COUNT_LENGTH)-1)
> +#define PRESCALER_MAX 6
>
>
> /*---------------------------------------------------------------------------*/
> /** @brief IWDG Enable Watchdog Timer
> @@ -73,42 +74,41 @@ reset until a system reset is issued.
>
> void iwdg_set_period_ms(uint32_t period)
> {
> - uint32_t count, prescale, reload, exponent;
> -
> - /* Set the count to represent ticks of the 32kHz LSI clock */
> - count = (period << 5);
> -
> - /* Strip off the first 12 bits to get the prescale value required */
> - prescale = (count >> 12);
> - if (prescale > 256) {
> - exponent = IWDG_PR_DIV256; reload = COUNT_MASK;
> - } else if (prescale > 128) {
> - exponent = IWDG_PR_DIV256; reload = (count >> 8);
> - } else if (prescale > 64) {
> - exponent = IWDG_PR_DIV128; reload = (count >> 7);
> - } else if (prescale > 32) {
> - exponent = IWDG_PR_DIV64; reload = (count >> 6);
> - } else if (prescale > 16) {
> - exponent = IWDG_PR_DIV32; reload = (count >> 5);
> - } else if (prescale > 8) {
> - exponent = IWDG_PR_DIV16; reload = (count >> 4);
> - } else if (prescale > 4) {
> - exponent = IWDG_PR_DIV8; reload = (count >> 3);
> - } else {
> - exponent = IWDG_PR_DIV4; reload = (count >> 2);
> - }
> + uint8_t prescale = 0;
> +
> + /* Set the count to represent ticks of 8kHz clock (the 32kHz LSI clock
> + * divided by 4 = lowest prescaler setting)
> + */
> + uint32_t count = period << 3;
>
> - /* Avoid the undefined situation of a zero count */
> + /* Prevent underflow */
> if (count == 0) {
> count = 1;
> }
>
> + /* Shift count while increasing prescaler as many times as needed to
> + * fit into IWDG_RLR
> + */
> + while ((count-1) >> COUNT_LENGTH) {
> + count >>= 1;
> + prescale++;
> + }
> +
> + /* IWDG_RLR actually holds count - 1 */
> + count--;
> +
> + /* Clamp to max possible period */
> + if (prescale > PRESCALER_MAX) {
> + count = COUNT_MASK;
> + prescale = PRESCALER_MAX;
> + }
> +
> while (iwdg_prescaler_busy());
> IWDG_KR = IWDG_KR_UNLOCK;
> - IWDG_PR = exponent;
> + IWDG_PR = prescale;
> while (iwdg_reload_busy());
> IWDG_KR = IWDG_KR_UNLOCK;
> - IWDG_RLR = (reload & COUNT_MASK);
> + IWDG_RLR = count & COUNT_MASK;
> }
>
>
> /*---------------------------------------------------------------------------*/
> --
> 2.11.0
>
>
>
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> libopencm3-devel@lists.sourceforge.net
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