im "SPEAK.spin"
)Code: Alles auswählen
'*********************************************************************************************************
i2c_read andn dira, _sdamask ' set sda to input
mov _data, #0
mov _loop_cnt, #8
mov _delay, cnt
add _delay, _i2cd
:bit_loop waitcnt _delay, _i2cd ' delay 1/4 period
shl _data, #1
or outa, _sclmask ' set clock high
waitcnt _delay, _i2cd ' delay 1/4 period
and _sdamask, ina wz, nr ' test data input bit
if_nz add _data, #1 ' set bit in output data if input bit was high
waitcnt _delay, _i2cd ' delay 1/4 period
andn outa, _sclmask ' set clock low
waitcnt _delay, _i2cd ' delay 1/4 period
djnz _loop_cnt, #:bit_loop
cmp _count, #1 wz, nr ' see if this is not the last byte to read
if_nz andn outa, _sdamask ' generate an ack by setting sda low
if_z or outa, _sdamask ' generate a nack
or dira, _sdamask ' set sda back to output
waitcnt _delay, _i2cd ' delay 1/4 period
or outa, _sclmask ' set clock high
waitcnt _delay, _i2cd ' delay 1/4 period
waitcnt _delay, _i2cd ' delay 1/4 period
andn outa, _sclmask ' set clock low
waitcnt _delay, _i2cd ' delay 1/4 period
shl _data, #24 ' <-- Das gelesene Byte wird 24x nach links geshiftet = 32 Bit Wert
mov frqa, _data ' <-- Der 32-Bit Wert wird in Counter A (frqa) geschrieben
i2c_read_ret ret
'*********************************************************************************************************
