Looking for Simple DAC and ADC Spin2 Examples

Duane Degn · 2020-08-26 15:12

I really enjoyed reading JonnyMac's Nuts&Volts article. It really helped me understand the PWM mode of the Smartpins. Are there similar examples on how to use the Propeller 2's Smartpins in DAC and ADC modes?

I've been trying to catch up on all the relevant P2 threads hoping to make sense of DAC and ADC modes but I'm going to cry "Uncle" and ask for help.

I don't need fast response times for either the DAC or the ADC. I'm hoping for an example similar to Jon's PWM code:

pub start(pin, duty, hz) | x

‘’ Configure smart pin for DMX-compatible PWM
‘’ --  pin - output pin (0..55)
‘’ -- duty - duty cycle of output 0 to 255 (100%)
‘’ --   hz - pwm output frequency

  if (hz > 0)
    pp := pin
    x.word[1] := 255
    x.word[0] := 1 #> ((clkfreq / 255) / hz) <# $FFFF
    pinstart(pin, P_OE | P_PWM_SAWTOOTH, x, duty)

Ideally an example I can use with the Propeller Tool.

kwinn · 2020-08-26 16:20

Here is one by Chip

kwinn · 2020-08-26 16:21

That's odd. Two copies added???

And one deleted.

Duane Degn · 2020-08-26 16:43

kwinn wrote: »

Here is one by Chip

Thanks kwinn but I'm looking for Propeller 2 Smartpin examples.

JonnyMac · 2020-08-26 18:26

I haven't done a DAC object yet, but here's a simple ADC object that uses Smart Pins.

-- https://github.com/parallaxinc/propeller/tree/master/libraries/community/p2/All/jm_ez_analog

JonnyMac · 2020-08-26 18:31

I used inline PASM in that code. You could also setup the Smart Pin and configuration values in Spin2.

Instead of:

  org
                fltl      pin                                   ' reset smart pin
                wrpin     ##(P_ADC | P_ADC_GIO), pin            ' read ground reference
                wxpin     #%00_1101, pin                        ' 8192 samples
                wypin     #0, pin                                
                dirh      pin                                   ' enable
                waitx     ##(8192 << 2)                         ' allow 4x readings
                rdpin     clo, pin                              ' save ground cal level
                                                                 
                fltl      pin                                   ' reset smart pin
                wrpin     ##(P_ADC | P_ADC_VIO), pin            ' read 3.3v reference
                wxpin     #%00_1101, pin                        ' 8192 samples
                wypin     #0, pin                                
                dirh      pin                                   ' enable
                waitx     ##(8192 << 2)                         ' allow 4x readings
                rdpin     chi, pin                              ' save Vio (3.3v) cal level
                                                                 
                fltl      pin                                   ' reset smart pin
                wrpin     ##(P_ADC | P_ADC_1X), pin             ' read input, no scaling
                wxpin     #%00_1101, pin                        ' 8192 samples
                wypin     #0, pin                                
                dirh      pin                                   ' enable
  end

... you should be able to do this...

  pinstart(pin, P_ADC | P_ADC_GIO, #%00_1101, 0)
  waitms(1)
  clo := rdpin(pin)
  pinstart(pin, P_ADC | P_ADC_VIO, #%00_1101, 0)
  waitms(1)
  chi := rdpin(pin)
  pinstart(pin, P_ADC | P_ADC_1X, #%00_1101, 0)
  waitms(1)

Duane Degn · 2020-08-26 18:38

JonnyMac wrote: »

here's a simple ADC object that uses Smart Pins.

I didn't read the details well enough when I saw that earlier. I erroneously assumed it was just a quadrature encoder example. Thank for help on this.

I really appreciate all the help you provide here.