transmit and receive side of a serial connection

serial communication

transmit side:

: send_byte ( n -- )  \ send byte as 8 bits
    ' TXP! 'EMIT !
    8 .R
    ' EMIT 'EMIT !
;

VARIABLE STATE
VARIABLE REM
VARIABLE QUOT
: trans \ to be run in idle task
    timer2 tTest IF
        95 send_byte \ '_' - "do nothing"
    ELSE
        \ send average in 2 bytes plus 1 byte CRC
        STATE @ 0= IF
            \ send a byte each time called

            \ scana ADCVAR @ DROP \ drop the first one
            \ scana ADCVAR @ \ current
            ADCVAR @ \ current

            330 4095 */ \ scale for current - still more than one byte
            255 /MOD ( REM QUOT ) \ split into bytes
            DUP QUOT ! \ store quotient
            send_byte \ send quotient
            REM ! \ store remainder
            1 STATE !
        THEN

        STATE @ 1 = IF
            REM @ \ fetch remainder
            send_byte \ send remainder
            2 STATE !
        THEN

        STATE @ 2 = IF
            REM @ \ fetch remainder
            QUOT @ \ fetch quotient
            -1 ROT ROT CRC16
            send_byte \ send remainder
            0 STATE !
        THEN

        timer2 3000 tSet count2
    THEN
;

receive side:

VARIABLE STATE
VARIABLE CURRENT
VARIABLE CTMPA
VARIABLE CTMPB
\ receiver:
\ wait? -> state 0
\ receive X-> state1
\ receive X-> state2
\ receive C-> state3
\ check. repeat
: rec1
    ?RXP IF
        DUP 95 = IF \ '_' (ascii 95) wait? -> state 0.
            0 STATE !
            DROP
        ELSE \ some incoming bits
            STATE @ 0 = IF \ quotient on top of stack
                CTMPA !
                1 STATE !
            THEN

            STATE @ 1 = IF \ remainder on top of stack
                CTMPB !
                2 STATE !
            THEN

            STATE @ 2 = IF \ crc on top of stack
                >R  \ hold this please
                CTMPB @ CTMPA @ 2DUP -1 ROT ROT ( CTMPB CTMPA -1 CTMPB CTMPA )
                CRC16
                R>  \ thank you
                = IF \ CRC MATCH
                    255 * + CURRENT !
                ELSE \ CRC FAIL
                    DROP \ keep present value for CURRENT
                THEN
                0 STATE !
            THEN
        THEN
    THEN
;