Bootloader

Is the bootloader for the sensor watch available? What's the process for flashing from scratch?

Apologies if it's somewhere obvious.

[joeycastillo]

No need to apologize, it is in fact not anyplace obvious. Here's the link; it's a fork of Adafruit's UF2 bootloader with support for the SAM L21 and SAM L22.

The process for flashing from scratch involves connecting to the five test points on the front of the Sensor Watch board, either by soldering to them or using pogo pins. You can use a PyRuler or Adafruit Trinket and this Arduino sketch to flash a precompiled bootloader to the board; this will also set the BOOTPROT fuses to prevent the bootloader from getting overwritten accidentally. (the sketch also requires the Adafruit_DAP Arduino library.

Hope this helps! Also I'm going to leave this issue open because I do need to put this documentation somewhere so it's easier to find; I will close it once that's in place :)

Thanks so much, you are eternally helpful!

Hi Joey, I got it working, but I did have to modify the adafruit DAP library to add the correct SAML chip. Something like:

diff --git a/Adafruit_DAP_SAM.cpp b/Adafruit_DAP_SAM.cpp
index 957183a..a92da31 100644
--- a/Adafruit_DAP_SAM.cpp
+++ b/Adafruit_DAP_SAM.cpp
@@ -109,6 +109,7 @@ device_t Adafruit_DAP_SAM::devices[] = {
     {0x1081020f, (char *)"SAM L21J18B (Rev C)", 256 * 1024, 4096},
     {0x1081021e, (char *)"SAM R30G18A", 256 * 1024, 4096},
     {0x1081021f, (char *)"SAM R30E18A", 256 * 1024, 4096},
+    {0x10820105, (char *)"SAM L22J18A", 256 * 1024, 4096},
     {0},
 };

Did you have to do this too, or I did I miss something? Also, is this patch correct if so?
If so, maybe we should document it somewhere or potentially upstream the DID support

[joeycastillo]

You are so right, I did have to make that change to Adafruit_DAP, and we should endeavor to upstream that support.

I can get on that some point in the next couple weeks, no worries