3 bugs fixed. Only tested on samd51

[slyalfa]

1: Fix for baud samd21 vs samd51
2: Added fix for first run where super slow first run of crc would cause
overruns on USART.
3: Prevent GCC from optimizing out a busy wait loop in Xmodem code

[dhalbert]

This looks fine! We never use the UART bootloader, but these changes should not affect the non-UART part, and they look perfectly reasonable.

[leomar95]

Hi @slyalfa. I'm trying to upload the Metro-M4 bord with us using BOSSA. Sometimes it worked. I think that art communication enters a timeout.

Did you have tried to update via bossa?

[slyalfa]

You need a current version. Ether download and make or use the one from the downloaded arduino. Anything apt-get seems to be very very old An example flash from my laptop with a cheap usb rs232 dongle.may need to do a sudo chmod 777 /dev/"whaterver com port you use" .arduino15/packages/arduino/tools/bossac/1.8.0-48-gb176eee/bossac -i -d --port=ttyUSB0 -U -i --offset=0x4000 -w -v /tmp/arduino_build_716231/scan.ino.bin -R I have a cap/diode circuit from dtr to reset so it just downloads without having to do anything I am not using USB at allI have the bootloader configes # edit inc/uf2.h    note this is enable not port number// Support the UART (real serial port, not USB)#define USE_UART 1 // Fine-tuning of features#define USE_HID_SERIAL 0   // just an example, not really needed; 36 bytes#define USE_HID_EXT 0      // extended HID commands (read/write mem); 60 bytes#define USE_HID_HANDOVER 0 // allow HID application->bootloader seamless transition; 56 bytes#define USE_MSC_HANDOVER 0 // ditto for MSC; 348 bytes#define USE_MSC_CHECKS 0   // check validity of MSC commands; 460 bytes#define USE_CDC_TERMINAL 0 // enable ASCII mode on CDC loop (not used by BOSSA); 228 bytes#define USE_DBG_MSC 0      // output debug info about MSC On Wednesday, August 5, 2020, 12:09:47 PM PDT, leomar95 <notifications@github.com> wrote: Hi @slyalfa. I'm trying to upload the Metro-M4 card with us using BOSSA. Sometimes it worked. I think that art communication enters a timeout. Have you tried to update via bossa? — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub, or unsubscribe.

[leomar95]

I was programming my board with PL2303(usb-serial). That was the problem. I tested without a converter and everything worked.

Thanks for your help @slyalfa