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Diffstat (limited to 'keyboards/hhkb/rn42/suart.S')
| -rw-r--r-- | keyboards/hhkb/rn42/suart.S | 156 |
1 files changed, 156 insertions, 0 deletions
diff --git a/keyboards/hhkb/rn42/suart.S b/keyboards/hhkb/rn42/suart.S new file mode 100644 index 000000000..09c45ce23 --- /dev/null +++ b/keyboards/hhkb/rn42/suart.S @@ -0,0 +1,156 @@ +;---------------------------------------------------------------------------; +; Software implemented UART module ; +; (C)ChaN, 2005 (http://elm-chan.org/) ; +;---------------------------------------------------------------------------; +; Bit rate settings: +; +; 1MHz 2MHz 4MHz 6MHz 8MHz 10MHz 12MHz 16MHz 20MHz +; 2.4kbps 138 - - - - - - - - +; 4.8kbps 68 138 - - - - - - - +; 9.6kbps 33 68 138 208 - - - - - +; 19.2kbps - 33 68 102 138 173 208 - - +; 38.4kbps - - 33 50 68 85 102 138 172 +; 57.6kbps - - 21 33 44 56 68 91 114 +; 115.2kbps - - - - 21 27 33 44 56 + +.nolist +#include <avr/io.h> +.list + +#define BPS 44 /* Bit delay. (see above table) */ +#define BIDIR 0 /* 0:Separated Tx/Rx, 1:Shared Tx/Rx */ + +#define OUT_1 sbi _SFR_IO_ADDR(SUART_OUT_PORT), SUART_OUT_BIT /* Output 1 */ +#define OUT_0 cbi _SFR_IO_ADDR(SUART_OUT_PORT), SUART_OUT_BIT /* Output 0 */ +#define SKIP_IN_1 sbis _SFR_IO_ADDR(SUART_IN_PIN), SUART_IN_BIT /* Skip if 1 */ +#define SKIP_IN_0 sbic _SFR_IO_ADDR(SUART_IN_PIN), SUART_IN_BIT /* Skip if 0 */ + + + +#ifdef SPM_PAGESIZE +.macro _LPMI reg + lpm \reg, Z+ +.endm +.macro _MOVW dh,dl, sh,sl + movw \dl, \sl +.endm +#else +.macro _LPMI reg + lpm + mov \reg, r0 + adiw ZL, 1 +.endm +.macro _MOVW dh,dl, sh,sl + mov \dl, \sl + mov \dh, \sh +.endm +#endif + + + +;---------------------------------------------------------------------------; +; Transmit a byte in serial format of N81 +; +;Prototype: void xmit (uint8_t data); +;Size: 16 words + +.global xmit +.func xmit +xmit: +#if BIDIR + ldi r23, BPS-1 ;Pre-idle time for bidirectional data line +5: dec r23 ; + brne 5b ;/ +#endif + in r0, _SFR_IO_ADDR(SREG) ;Save flags + + com r24 ;C = start bit + ldi r25, 10 ;Bit counter + cli ;Start critical section + +1: ldi r23, BPS-1 ;----- Bit transferring loop +2: dec r23 ;Wait for a bit time + brne 2b ;/ + brcs 3f ;MISO = bit to be sent + OUT_1 ; +3: brcc 4f ; + OUT_0 ;/ +4: lsr r24 ;Get next bit into C + dec r25 ;All bits sent? + brne 1b ; no, coutinue + + out _SFR_IO_ADDR(SREG), r0 ;End of critical section + ret +.endfunc + + + +;---------------------------------------------------------------------------; +; Receive a byte +; +;Prototype: uint8_t rcvr (void); +;Size: 19 words + +.global rcvr +.func rcvr +rcvr: + in r0, _SFR_IO_ADDR(SREG) ;Save flags + + ldi r24, 0x80 ;Receiving shift reg + cli ;Start critical section + +1: SKIP_IN_1 ;Wait for idle + rjmp 1b +2: SKIP_IN_0 ;Wait for start bit + rjmp 2b + ldi r25, BPS/2 ;Wait for half bit time +3: dec r25 + brne 3b + +4: ldi r25, BPS ;----- Bit receiving loop +5: dec r25 ;Wait for a bit time + brne 5b ;/ + lsr r24 ;Next bit + SKIP_IN_0 ;Get a data bit into r24.7 + ori r24, 0x80 + brcc 4b ;All bits received? no, continue + + out _SFR_IO_ADDR(SREG), r0 ;End of critical section + ret +.endfunc + + +; Not wait for start bit. This should be called after detecting start bit. +.global recv +.func recv +recv: + in r0, _SFR_IO_ADDR(SREG) ;Save flags + + ldi r24, 0x80 ;Receiving shift reg + cli ;Start critical section + +;1: SKIP_IN_1 ;Wait for idle +; rjmp 1b +;2: SKIP_IN_0 ;Wait for start bit +; rjmp 2b + ldi r25, BPS/2 ;Wait for half bit time +3: dec r25 + brne 3b + +4: ldi r25, BPS ;----- Bit receiving loop +5: dec r25 ;Wait for a bit time + brne 5b ;/ + lsr r24 ;Next bit + SKIP_IN_0 ;Get a data bit into r24.7 + ori r24, 0x80 + brcc 4b ;All bits received? no, continue + + ldi r25, BPS/2 ;Wait for half bit time +6: dec r25 + brne 6b +7: SKIP_IN_1 ;Wait for stop bit + rjmp 7b + + out _SFR_IO_ADDR(SREG), r0 ;End of critical section + ret +.endfunc |