{LET} adcsetup = channels

Channels - is the number / mask of ADC to enable.

On M2, 28X2, 40X2 parts the appropriate adcsetup bit is set automatically by the readadc/readadc10/touch command. Therefore on these parts the only real use of adcsetup is to change a pin back from analogue to digital setup.

On older X2 parts (20X2, 28X2-5V, 28X2-3V, 40X2-5V, 40X2-3V) it is necessary to configure the ADC pins for use with the readadc/readadc10 commands. On all other parts this configuration is automatic.

Note that adcsetup is technically a variable (word length), not a command, and so can be used in let assignments and mathematics (e.g bit masking using & ). Using adcsetup does NOT actually 'connect' the internal adc to the input pin - the adc is always connected! Using adcsetup just disconnects the digital input buffer, so that the internal digital input circuitry does not effect the analogue reading. Therefore readadc commands may still work without correctly configuring adcsetup, however the analogue readings may not be as reliable as expected.

If a pin has been configured as an analogue input (adcsetup bit is set) then the normal 'digital' input circuit is internally disconnected. Therefore if you try to read the digital input (e.g. using if pinX.Y = 1 then) the result will always be 0. 

Due to advances in microcontroller technology the use of 'adcsetup' varies slightly according to the part in use. Please ensure you study the correct page for the part you are using.

There are separate sections for:

PICAXE-28X2 (PIC18F25K22), PICAXE-40X2 (PIC18F45K22) (not older -5V or -3V versions)

Individual Pin Masking

With individual pin masking any pin can be individually controlled. Setting the bit disconnects the corresponding digital input to dedicate to analogue operation.

Note that with these parts the appropriate bit is always automatically set upon any readadc / readadc10 / touch / touch16 command. Therefore the only real use of this command is to turn an analogue pin back into a digital pin by clearing the appropriate bit.

adcsetup variable:

adcsetup2 variable:

Voltage Reference

The default Vref+signal is the power supply (V+) and Vref- signal is 0V, so the analogue voltage range is the same as the power supply to the PICAXE chip. However, if desired, the Vref signals can be altered to external pins instead by using the adcconfig command.

PICAXE-28X2 -5V (PIC18F2520), PICAXE-40X2 -5V (PIC18F4520)

Sequential Masking

With sequential masking pins can only be configured for analogue readings if:

With the sequential system, for instance, it is only possible to enable ADC3 if ADC0-2 are also enabled. This is an internal design restraint of the PICmicro, not the PICAXE bootstrap. The number of channels and active ADC pins are shown below.   

ADC4,5,6,7 do not exist on the 28X2-5V parts.

ADC4 does not exist on the 40X2-5V parts.

Voltage Reference

The default Vref+signal is the power supply (V+) and Vref- signal is 0V, so the analogue voltage range is the same as the power supply to the PICAXE chip. However, if desired, the Vref signals can be altered to external pins instead by setting bits 15 and 14 of adcsetup.

PICAXE-20X2 (PIC18F14K22), PICAXE-28X2-3V (PIC18F25K20), PICAXE-40X2-3V (PIC18F45K20)

Individual Pin Masking

With individual pin masking any pin can be individually controlled. Setting the bit disconnects the corresponding digital input to dedicate to analogue operation.

Voltage Reference

The default Vref+signal is the power supply (V+) and Vref- signal is 0V, so the analogue voltage range is the same as the power supply to the PICAXE chip. However, if desired, the Vref signals can be altered to external pins instead by setting bits 15 and 14 of adcsetup.

ALL M2 series parts

Individual Pin Masking

With individual pin masking any pin can be individually controlled. Setting the bit disconnects the corresponding digital input to dedicate to analogue operation.

Note that with M2 parts the appropriate bit is always automatically set upon any readadc / readadc10 / touch / touch16 command. Therefore the only real practical use of this command is to turn an analogue pin back into a digital pin by clearing the appropriate bit.

08M2

14M2, 18M2, 20M2

Voltage Reference

The default Vref+signal is the power supply (V+) and Vref- signal is 0V, so the analogue voltage range is the same as the power supply to the PICAXE chip. However, if desired, the Vref signals can be altered to external pins instead by use of the adcconfig command.