/
i2c.inc
129 lines (110 loc) · 4.39 KB
/
i2c.inc
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eeprom_read
// Select the device & send address
call #i2c_start
mov i2c_data, i2c_addr
shr i2c_data, #15
and i2c_data, #$02
or i2c_data, #EEPROM_ADDR | I2C_WRITE
call #i2c_write
mov i2c_data, i2c_addr
shr i2c_data, #8
call #i2c_write
mov i2c_data, i2c_addr
call #i2c_write
// Reselect the device for reading
call #i2c_start
mov i2c_data, i2c_addr
shr i2c_data, #15
and i2c_data, #$02
or i2c_data, #EEPROM_ADDR | I2C_READ
call #i2c_write
// Read i2c_data
_l4r add i2c_addr, #1
cmp ccnt, #1 wz
if_z jmp #_l5r
test i2c_addr, block_boundary wz
if_z jmp #_l5r
mov ack, #I2C_ACK
call #i2c_read
wrbyte i2c_data, i2c_hub_addr
add i2c_hub_addr, #1
sub ccnt, #1
jmp #_l4r
_l5r mov ack, #I2C_NAK
call #i2c_read
wrbyte i2c_data, i2c_hub_addr
add i2c_hub_addr, #1
call #i2c_stop
djnz ccnt, #eeprom_read
eeprom_read_ret ret
i2c_start
or OUTA, i2c_scl
or DIRA, i2c_scl
nop
or OUTA, i2c_sda
or DIRA, i2c_sda
nop
nop
andn OUTA, i2c_sda
nop
andn OUTA, i2c_scl
nop
i2c_start_ret ret
// SDA goes LOW to HIGH with SCL High
i2c_stop
andn OUTA, i2c_scl
nop
andn OUTA, i2c_sda
nop
nop
andn DIRA, i2c_scl
nop
andn DIRA, i2c_sda
nop
i2c_stop_ret ret
i2c_write
mov mask, #$80
_l2 test i2c_data, mask wz
if_nz or OUTA, i2c_sda
if_z andn OUTA, i2c_sda
or OUTA, i2c_scl // Toggle SCL from LOW to HIGH to LOW
nop
nop
andn OUTA, i2c_scl
shr mask, #1 wz
if_nz jmp #_l2
andn DIRA, i2c_sda
nop
nop
or OUTA, i2c_scl
test i2c_sda, INA wc
rcl ack, #1
andn OUTA, i2c_scl
or OUTA, i2c_sda
or DIRA, i2c_sda
i2c_write_ret ret
i2c_read
mov i2c_data, #0
andn DIRA, i2c_sda
mov mask, #8
_l3
nop
nop
or OUTA, i2c_scl
test i2c_sda, INA wc
rcl i2c_data, #1
andn OUTA, i2c_scl
djnz mask, #_l3
cmp ack, #I2C_NAK wz
if_z or OUTA, i2c_sda
if_nz andn OUTA, i2c_sda
or DIRA, i2c_sda
or OUTA, i2c_scl
nop
nop
andn OUTA, i2c_scl
andn OUTA, i2c_sda
i2c_read_ret ret
i2c_addr long 0
i2c_hub_addr long 0
i2c_data long 0