stm32/adc: Apply re-read errata for WB55.

dpgeorge · dpgeorge · commit ea2000b81d20 · 2025-07-08T13:14:43.000+10:00
Following 17898f8. Signed-off-by: Damien George <damien@micropython.org>
diff --git a/ports/stm32/adc.c b/ports/stm32/adc.c
@@ -464,10 +464,13 @@ static void adc_config_channel(ADC_HandleTypeDef *adc_handle, uint32_t channel)
 
 static uint32_t adc_read_channel(ADC_HandleTypeDef *adcHandle) {
     uint32_t value;
-    #if defined(STM32G4)
-    // For STM32G4 there is errata 2.7.7, "Wrong ADC result if conversion done late after
-    // calibration or previous conversion".  According to the errata, this can be avoided
-    // by performing two consecutive ADC conversions and keeping the second result.
+    #if defined(STM32G4) || defined(STM32WB)
+    // For STM32G4 errata 2.7.7 / STM32WB errata 2.7.1:
+    // "Wrong ADC result if conversion done late after calibration or previous conversion"
+    // states an incorrect reading is returned if more than 1ms has elapsed since the last
+    // reading or calibration. According to the errata, this can be avoided by performing
+    // two consecutive ADC conversions and keeping the second result.
+    // Note: On STM32WB55 @ 64Mhz each ADC read takes ~ 3us.
     for (uint8_t i = 0; i < 2; i++)
     #endif
     {
