Copied all needed files.

[fpga/virtex2/uart.git] / software / swuart.s

diff --git a/software/swuart.s b/software/swuart.s
new file mode 100644 (file)
index 0000000..dc17823
--- /dev/null
+++ b/software/swuart.s
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+#include "hardware.h"
+
+;variables
+.data
+        .comm   rxdata,1,1              ;char var
+        .comm   rxshift,1,1             ;char var
+        .comm   rxbit,2,2               ;short var, aligned
+
+.text
+
+interrupt(TIMERA0_VECTOR)               ;register interrupt vector
+;interrupt handler to receive as Timer_A UART
+.global ccr0                            ;place a label afterwards so
+ccr0:                                   ;that it is used in the listing
+        add     rxbit, r0
+        jmp     .Lrxstart               ;start bit
+        jmp     .Lrxdatabit             ;D0
+        jmp     .Lrxdatabit             ;D1
+        jmp     .Lrxdatabit             ;D2
+        jmp     .Lrxdatabit             ;D3
+        jmp     .Lrxdatabit             ;D4
+        jmp     .Lrxdatabit             ;D5
+        jmp     .Lrxdatabit             ;D6
+;        jmp     .Lrxlastbit             ;D7 that one is following anyway
+        
+.Lrxlastbit:                            ;last bit, handle byte
+        bit     #SCCI, &CCTL0           ;read last bit
+        rrc.b   rxshift                 ;and save it
+        clr     rxbit                   ;reset state
+        mov     #CCIE|CAP|CM_2|CCIS_1|SCS, &CCTL0   ;restore capture mode
+        mov.b   rxshift, rxdata         ;copy received data
+        bic     #CPUOFF|OSCOFF|SCG0|SCG1, 0(r1) ;exit all lowpower modes
+        ;here you might do other things too, like setting a flag
+        ;that the wakeup comes from the Timer_A UART. however
+        ;it should not take longer than one bit time, otherwise
+        ;charcetrs will be lost.
+        reti
+
+.Lrxstart:                              ;startbit, init
+        clr     rxshift                 ;clear input buffer
+        add     #(BAUD/2), &CCR0        ;startbit + 1.5 bits -> first bit
+        mov     #CCIE|CCIS_1|SCS, &CCTL0;set compare mode, sample bits
+        jmp     .Lrxex                  ;set state,...
+
+.Lrxdatabit:                            ;save databit
+        bit     #SCCI, &CCTL0           ;measure databit
+        rrc.b   rxshift                 ;rotate in databit
+
+.Lrxex: add     #BAUD, &CCR0            ;one bit delay
+        incd    rxbit                   ;setup next state
+        reti
+
+; void serPutc(char)
+;use an other Capture/Compare than for receiving (full duplex).
+;this one is without interrupts and OUTMOD, because only
+;this way P1.1 can be used. P1.1 is prefered because the
+;BSL is on that pin too.
+.global putchar
+        .type putchar, @function
+putchar:                                ;send a byte
+        mov     #0, &CCTL1              ;select compare mode
+        mov     #10, r13                ;ten bits: Start, 8 Data, Stop
+        rla     r15                     ;shift in start bit (0)
+        bis     #0x0200, r15            ;set tenth bit (1), thats the stop bit
+        mov     &TAR, &CCR1             ;set up start time
+.Lt1lp: add     #BAUD, &CCR1            ;set up for one bit
+        rrc     r15                     ;shift data trough carry
+        jc      .Lt1                    ;test carry bit
+.Lt0:   bic.b   #TX, &P1OUT             ;generate pulse
+        jmp     .Ltc                    ;
+.Lt1:   bis.b   #TX, &P1OUT             ;just use the same amount of time as for a zero
+        jmp     .Ltc                    ;
+.Ltc:   bit     #CCIFG, &CCTL1          ;wait for compare
+        jz      .Ltc                    ;loop until the bit is set
+        bic     #CCIFG, &CCTL1          ;clear for next loop
+        dec     r13                     ;decrement bit counter
+        jnz     .Lt1lp                  ;loop until all bits are transmitted
+        ret