This port was done with a AT91SAM7S-EK which contained a
AT91SAM7S64 processor. The compiler was the GNU ARM compiler
and tools from Yagarto project.
The hardware was modified by severing the I-PA5 (RXD0),
I-PA6 (TXD0), I-PA7 (RTS0) pads and rerouting those
signals to a DS75176 RS-485 transceiver.
PIN SIGNAL AT91SAM7S
--- ------ ---------
1 RO RXD0
2 /RE RTS
3 DE RTS
4 DI TXD0
5 GND GND
6 DO n/c
7 DO n/c
8 +5V From EXT_VCC via 5V Regulator
The makefile allows you to build just the dlmstp or a simple
server, both for programming into the flash memory of the processor.
The dlmstp is the datalink layer for MS/TP over RS-485.
I used the makefile from the command line on Windows, and
then used the SAM-BA to send the resulting .bin file to the
board using a J-Link. To debug the code from flash, run the
J-Link GDB Server and then:
> arm-elf-gdb bacnet.elf
I got the crt.s, at91sam7s256.ld, blinker.c, init.c, isr.c, and
timer.c from James P Lynch. I created the rs485.c based on the
initialization sequence from serial.c by Keil Electronik. I
got the at91sam7s256.h file from Atmel via the Keil website.
I started with the makefile from James P Lynch, but it didn't work
for me. I then used some ideas from FreeRTOS makefile, and
created my own makefile from scratch.
Hopefully you find it useful!
Steve Karg
Steve Karg
7cb63dcf06