serial (PL011) config on RaspberryPi
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Date: Sun, 27 Oct 2024 19:21:47 UTC
Hi, I have a problem setting the speed of the physical UART on a Raspberry Pi 3B+. I want to connect a HP48 pocket calculator an Raspi serially via RS232. Raspi's running FreeBSD 14.1-RELEASE. Serial lines: RX,TX,Shield,GND (no CTS nor RTS) Finally I'll use Kermit but while here are issues, I first aim for serial running. That is: echo -n "S" > /dev/cuau0 # sending and: cat /dev/cuau0 # receiving ("S" = #53h = #01010011b) Watching on oscilloscope: Send signals can be observed from Raspi and Hp48. Config: edit: /etc/ttys Commented out all 'ttyuN' lines (0-3) cause that gave me access to 'cuau0' and disposed console butting in. Well: stty -a -f /dev/cuau0 speed 115200 baud; 0 rows; 0 columns; <snip> stty -f /dev/cuau0 speed 9600 115200 stty -a -f /dev/cuau0 speed 9600 baud; 0 rows; 0 columns; <snip> seems to work, however: echo -n "S" > /dev/cuau0 # sending from Raspi sends 8.62_µs a bit. That is 115200_baud. sending from HP48: sends 104.80_µs a bit. That's 9600_baud. cat /dev/cuau0 # doesn't receive anything, ofcause So: How to set the serial line's speed. (manually, after boot) Thanks in advance, Holger