Texas Instruments TMS320C2XX User Manual
Page 500
Task-Specific Program Code
C-15
Program Examples
Example C–10. Loopback to Verify Transmissions of Asynchronous Serial Port (echo.asm)
(Continued)
* UART initialization *
splk
#0ffffh,ifr
; clear interrupts
splk
#0000h,60h
out
60h, wsgr
; Set zero wait states
splk
#0c080h,61h
; reset the UART by writing 0
out
61h, aspcr
; 1 stop bit, rx interrupt, input i/o
splk
#0e080h,61h
out
61h,aspcr
splk
#4fffh,62h
out
62h,iosr
; disable auto baud
splk
#0411h, 63h
; set baud rate =1200 @ 20MHz CLKOUT1
out
63h, brd
splk
#20h,imr
; enable UART interrupt
mar
*,ar1
* Load data at DM300
lar
ar1,#rxbuf
lar
ar0, #size
; load buffer size
mar
*,ar1
; load data pointer
clrc intm
wait:
clrc
xf
; toggle xf bit
idle
b
wait
uart:
setc
xf
; toggle xf bit
; Check receive flag bit in iosr
in
68h,iosr
; load input status from iosr
bit
68h,7
; bit 8 in the data
bcnd
skip,ntc
; IF DR=0 no echo, return
in
*,adtr
; read and save at 300h
out
*+,adtr
; echo
mar
*,ar0
banz
skip,ar1
; check if size=0, and reload
lar
ar1,#rxbuf
lar
ar0,#size
skip:
splk
#0020h, ifr
; Clear interrupt in ifr!
clrc
intm
ret
inpt1:
ret
inpt23:
ret
timer:
ret
codtx:
ret
codrx:
ret
.end
; Assembler module end directive
; –optional