MAX31855 pin mapping

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Roy Johnston
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MAX31855 pin mapping

Post by Roy Johnston »

I am a bit confused
The component has a pin remapping option on the MOSI, MISO and CLK pins. CS/SS pins are selectable. I don’t want to remap the pins. I want to wire the actual pins specified in the chip datasheet
This component only requires 3 connections. MISO, SCK and CS
I will obviously not wire MOSI pin. Can I use this pin elsewhere for either an outputs or inputs.
I am using channel 2 for my projects. the greyed-out values namely D5, D6 and D7 are the pins where I will wire my chips onto. What happens to the remapped pins? can I use the mapped pins elsewhere in my project?

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Benj
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Re: MAX31855 pin mapping

Post by Benj »

Hello Roy,

On some target chips the SPI and other peripherals can be assigned to various IO pins. When this is an option the remap properties become active allowing you to select which IO pins you want to use.

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Bachman
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Re: MAX31855 pin mapping

Post by Bachman »

When you're using SPI HW module in the controller, the module will dominate the MOSI, MISO, SCK pins. In this case, if you're not using MISO pin, you can use it as a digital input, but only as a digital input. The corresponding bit of the PORT register (in PIC microcontrollers) can be read and it will show the correct input value of the pin. MOSI and SCK pins can't be use to other things.

For MAX31855, the MISO pin must be the data pin while wasting of the MOSI pin, except if you're using software SPI mode.

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