Mercurial > hg > Members > kono > nitros9-code
view level1/modules/dwwrite.asm @ 2242:2a889a511f0a
Adding Aaron Wolfe's DriveWire work
| author | boisy |
|---|---|
| date | Thu, 24 Dec 2009 01:16:31 +0000 |
| parents | 27f07aa0bca0 |
| children | f0977fc3f2d6 |
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******************************************************* * * DWWrite * Send a packet to the DriveWire server. * Serial data format: 1-8-N-1 * 4/12/2009 by Darren Atkinson * * Entry: * X = starting address of data to send * Y = number of bytes to send * * Exit: * X = address of last byte sent + 1 * Y = 0 * All others preserved * IFNE BAUD38400 ******************************************************* * 38400 bps using 6809 code and timimg ******************************************************* DWWrite pshs u,d,cc ; preserve registers orcc #$50 ; mask interrupts ldu #BBOUT ; point U to bit banger out register lda 3,u ; read PIA 1-B control register anda #$f7 ; clear sound enable bit sta 3,u ; disable sound output fcb $8c ; skip next instruction txByte stb ,--u ; send stop bit leau ,u+ lda #8 ; counter for start bit and 7 data bits ldb ,x+ ; get a byte to transmit lslb ; left rotate the byte two positions.. rolb ; ..placing a zero (start bit) in bit 1 tx0010 stb ,u++ ; send bit tst ,--u rorb ; move next bit into position deca ; decrement loop counter bne tx0010 ; loop until 7th data bit has been sent leau ,u stb ,u ; send bit 7 lda ,u++ ldb #$02 ; value for stop bit (MARK) leay -1,y ; decrement byte counter bne txByte ; loop if more to send stb ,--u ; leave bit banger output at MARK puls cc,d,u,pc ; restore registers and return ELSE IFNE H6309-1 ******************************************************* * 57600 (115200) bps using 6809 code and timimg ******************************************************* DWWrite pshs dp,d,cc ; preserve registers orcc #$50 ; mask interrupts ldd #$04ff ; A = loop counter, B = $ff tfr b,dp ; set direct page to $FFxx setdp $ff ldb <$ff23 ; read PIA 1-B control register andb #$f7 ; clear sound enable bit stb <$ff23 ; disable sound output fcb $8c ; skip next instruction txByte stb <BBOUT ; send stop bit ldb ,x+ ; get a byte to transmit nop lslb ; left rotate the byte two positions.. rolb ; ..placing a zero (start bit) in bit 1 tx0020 stb <BBOUT ; send bit (start bit, d1, d3, d5) rorb ; move next bit into position exg a,a nop stb <BBOUT ; send bit (d0, d2, d4, d6) rorb ; move next bit into position leau ,u deca ; decrement loop counter bne tx0020 ; loop until 7th data bit has been sent stb <BBOUT ; send bit 7 ldd #$0402 ; A = loop counter, B = MARK value leay ,-y ; decrement byte counter bne txByte ; loop if more to send stb <BBOUT ; leave bit banger output at MARK puls cc,d,dp,pc ; restore registers and return setdp $00 ELSE ******************************************************* * 57600 (115200) bps using 6309 native mode ******************************************************* DWWrite pshs u,d,cc ; preserve registers orcc #$50 ; mask interrupts * ldmd #1 ; requires 6309 native mode ldu #BBOUT+1 ; point U to bit banger out register +1 aim #$f7,2,u ; disable sound output lda #8 ; counter for start bit and 7 data bits fcb $8c ; skip next instruction txByte stb -1,u ; send stop bit tx0010 ldb ,x+ ; get a byte to transmit lslb ; left rotate the byte two positions.. rolb ; ..placing a zero (start bit) in bit 1 bra tx0030 tx0020 bita #1 ; even or odd bit number ? beq tx0040 ; branch if even (15 cycles) tx0030 nop ; extra (16th) cycle tx0040 stb -1,u ; send bit rorb ; move next bit into position deca ; decrement loop counter bne tx0020 ; loop until 7th data bit has been sent leau ,u+ stb -1,u ; send bit 7 ldd #$0802 ; A = loop counter, B = MARK value leay -1,y ; decrement byte counter bne txByte ; loop if more to send stb -1,u ; final stop bit puls cc,d,u,pc ; restore registers and return ENDC ENDC