esp32: Pin MicroPython and NimBLE tasks to core 0.

MicroPython and NimBLE must be on the same core, for synchronisation of the
BLE ringbuf and the MicroPython scheduler.  However, in the current IDF
versions (3.3 and 4.0) there are issues (see e.g. #5489) with running
NimBLE on core 1.

This change - pinning both tasks to core 0 - makes it possible to reliably
run the BLE multitests on esp32 boards.

1 files changed, 5 insertions, 2 deletions

diff --git a/ports/esp32/mphalport.h b/ports/esp32/mphalport.h
index 1f78d820a..60cc308d6 100644
--- a/ports/esp32/mphalport.h
+++ b/ports/esp32/mphalport.h
@@ -35,8 +35,11 @@
 #include "freertos/FreeRTOS.h"
 #include "freertos/task.h"
 
-// The core that the MicroPython task(s) are pinned to
-#define MP_TASK_COREID (1)
+// The core that the MicroPython task(s) are pinned to.
+// Until we move to IDF 4.2+, we need NimBLE on core 0, and for synchronisation
+// with the ringbuffer and scheduler MP needs to be on the same core.
+// See https://github.com/micropython/micropython/issues/5489
+#define MP_TASK_COREID (0)
 
 extern TaskHandle_t mp_main_task_handle;