Invalid baud rate set by blhost when updating over UART (Linux host)

alexfeinman — Wed, 09 Nov 2016 00:17:42 GMT

This is actually two-part thing.

1. BLHOST ignores baud rate setting. Here is a snippet from serial.c (KBOOT 2.0)

switch (speed)

{
case 9600:
speed = B9600;
break;
case 38400:
speed = B38400;
break;
case 115200:
speed = B115200;
break;
case 57600:
default:
speed = B57600;
break;
}
cfsetospeed(&tty, B57600);
cfsetispeed(&tty, B57600);

Quite obviously the requested baud rate is being simply ignored in favor of 57600

This was supposed to be

cfsetospeed(&tty, speed);
cfsetispeed(&tty, speed);

2. Even worse - the baud rate is then overwritten in serial_set_read_timeout

memset(&tty, 0x00, sizeof(tty));
cfmakeraw(&tty);
set a bunch of flags (but not speed)
if (tcsetattr(fd, TCSAFLUSH, &tty) < 0)
{
return -1;
}

For this to work properly it needs to be:

tcgetattr(fd, &tty);

instead of

cfmakeraw(&tty);

Since most testing at Freescale has been obviously done on FRDM boards which use cdc_acm driver, this has not been an issue since cdc_acm driver ignores invalid baud rate (0 is invalid). However CP210x driver (Silicon Labs) assumes 300 bps (FTDI defaults to 9600). This results in time required to flash a small 50KB image being about 1hr.

Re: Invalid baud rate set by blhost when updating over UART (Linux host)

dellgreen — Wed, 23 Oct 2019 05:57:40 GMT

Did this ever get patched, or is there patches available to fix this?

Re: Invalid baud rate set by blhost when updating over UART (Linux host)

dellgreen — Wed, 23 Oct 2019 06:07:37 GMT

Looks like 3rd party fork and fixes can be found here:

Commits · Lauszus/blhost · GitHub

topic Re: Invalid baud rate set by blhost when updating over UART (Linux host) in MCU Bootloader

Invalid baud rate set by blhost when updating over UART (Linux host)

Re: Invalid baud rate set by blhost when updating over UART (Linux host)

Re: Invalid baud rate set by blhost when updating over UART (Linux host)