12 - 16b ADC

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26 Jan 2017 17:55 #86723 by Bari
12 - 16b ADC was created by Bari
Is there an off the shelf solution to get a 12 - 16b ADC input (few samples per second) for HAL?

Maybe an ADC board with SPI or even serial at this low speed.

SPI
github.com/LinuxCNC/linuxcnc/blob/master...onents/max31855.comp

Serial
www.linuxcnc.org/docs/html/man/man9/serport.9.html

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26 Jan 2017 18:16 #86727 by Bari
Replied by Bari on topic 12 - 16b ADC
Just discovered this older thread:
forum.linuxcnc.org/24-hal-components/292...ul-i2c-communication

Might be able to just use the Mesa THC 10V board as well, but it's kind of goofy to go voltage --> frequency --> voltage but it's <$70

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26 Jan 2017 18:35 #86728 by PCW
Replied by PCW on topic 12 - 16b ADC
You could use a 7I87
This has 8 12 bit +-10V inputs updated at the servo thread rate

If its quite slow you might be able to use a generic USB A-D with a userland interface

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26 Jan 2017 18:40 #86729 by Todd Zuercher
Replied by Todd Zuercher on topic 12 - 16b ADC
The Mesa 7i87 has a 12-bit ADC, might that be good enough?
store.mesanet.com/index.php?route=produc...69_70&product_id=126

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26 Jan 2017 18:43 #86730 by Bari
Replied by Bari on topic 12 - 16b ADC
Yeah, just need a few samples per second is all. How did I miss this?

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27 Jan 2017 05:51 #86763 by Bari
Replied by Bari on topic 12 - 16b ADC
Seb also posted this:
github.com/SebKuzminsky/linuxcnc-hal-teensy

Software for plugging a Teensy 3.x into LinuxCNC's HAL. It supports digital inputs and outputs, analog input, analog output (via the Teensy DAC) and PWM output (via the Teensy "analog output" pins).

This project was forked from apmorton's teensy-template, github.com/apmorton/teensy-template

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27 Jan 2017 13:39 #86780 by andypugh
Replied by andypugh on topic 12 - 16b ADC
Just for fun, here is an idea for parallel port analogue input that I had a while ago.

Use a PWMgen into a filter to create an analogue voltage.
Use a hardware comparator to feed back a "too high / too low signal" on a second digital pin.
Use a HAL component to track the PWM duty cycle to the high/low pin value.
Use the PWM duty cycle resulting as your measurement.

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