3.4 AD/DA

PCF 8591A is simple AD and DA converter. Designed for I2C bus is directly connectable to Z-Berry.

Here is an example how easy it is to write code to read data from A/D converter using built-in routines in ROM.

DA: CALL SYS_I2C_START ; start cond.

LD C, DEV_ADDR ; send device address

CALL SYS_I2C_WRITE ; and device setting

LD C, %01000100 ; enable output, 4 single inputs, autoincrement

CALL SYS_I2C_WRITE

LD C, DA_VALUE ; finally D/A value

CALL SYS_I2C_WRITE

CALL SYS_I2C_STOP ; stop cond.

AD: LD IX, TEMP ; place to write data

CALL SYS_I2C_START ; start cond.

LD C, DEV_ADDR+1 ; send device address + read bit

CALL SYS_I2C_WRITE

CALL SYS_I2C_RDACK ; and four readings

LD (IX+0), C

CALL SYS_I2C_RDACK

LD (IX+1), C

CALL SYS_I2C_RDACK

LD (IX+2), C

CALL SYS_I2C_RDNACK; say no more readings

LD (IX+3), C

CALL SYS_I2C_STOP ; stop cond.