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nerdyscout / Arduino_MCP3x6x_Library

Library to support Microchip MPC3x6x 16/24bit analog to digital converters.
https://nerdyscout.github.io/Arduino_MCP3x6x_Library
MIT License
17 stars 9 forks source link

Some questions about the SPI #10

Closed FelixWT closed 1 year ago

FelixWT commented 1 year ago

Recently I run in to some issue that got me good : that is the timming of CS pin pulldown https://github.com/nerdyscout/Arduino_MCP3x6x_Library/blob/6cce10135956cceaa817b629f27d1a70c646e8a2/lib/MCP3x6x/MCP3x6x.cpp#L80-L90 As above in your code CS pin is pulldowned after beginTransaction function been called , and it works! But when i'm using another adc (Texas Instrument's ads8691) it have to pulldown before it So my question is how do I know when do I need to place it before or after beginTransaction function call ?

Another question: does the noInterrupts(); effect on the Interrupts that was pinned to another esp32 core?

Mirageofmage commented 1 year ago

The CS pin is typically pulled low after beginTransaction. See the Arduino SPITransaction documentation.

The interrupts() and noInterrupts() can be removed.

Also, are you trying to use this library with the ads8691 ADC? This library is only for the MCP3x6x line from Microchip?

FelixWT commented 1 year ago

The CS pin is typically pulled low after beginTransaction

This is what I thought at first , But for ads8691 it's not .I assume I have to trail error when ever it work abnormally?

Also, are you trying to use this library with the ads8691 ADC?

No I use this amazing library as the base structure for that ADC

nerdyscout commented 1 year ago

hi @FelixWT, I wrote this lib primarily with the SAMD21 in mind I am using it with but tried to keep it open to many other controllers. So I never tried any ESP by myself, hard to say what a multi core mcu does.

Setting up SPI Settings first, than pulling CS low seems the logical way to me. did you double check settings according to "7.5.4.1 Protocols for Configuring the Device"

@Mirageofmage I would be careful about removing noInterrupts(). I had some bad effects doing so! But you could also run into trouble as I assume no other interrupts (USB, watchdog , wifi, ....) will be handled while running though this code

FelixWT commented 1 year ago

did you double check settings according to "7.5.4.1 Protocols for Configuring the Device"

yes I did, it only discribes the SPI Mode. I assume it's something to do with the recognition time of CS PIN change.