Using Aux0 on MiniPCB2 for Limit Switches


Stephen J McIntyre
 

I am planning on using the Aux0 (pin 19) on the MiniPCB2 to read the input from the mount's limit switches.  

The pinmap and code appear to support this configuration. However, Aux0 does not have a capacitor to protect against ESD. Do i need to add a 0.1uf capacitor if using Aux0 for an input? (Aux3/4 and the PEC inputs include this capacitor.)

The pullup resistor on Aux0 will be 3.3kohm resistor instead of the 2k used on the Aux3 input, but since this change is similar to repurposing Aux4 as an input and it has a 3.3k resistor, i am assuming this will be ok. 

I also plan on using Aux3/4 for home sense switches. And support PEC. As far as i can figure, Aux0 was the only pin available that i could repurpose for the limit switches. I think i can do without the status indication that is provided by STA1 (D3).

To repurpose Aux4 and Aux0 from status LED outputs to read inputs, i will replace the LEDs D2 and D3 with a shunt.  

My configuration:
CGE Pro
MiniPCB2
Teensy 4.0
TCM5160 drivers
400step, 1.7a stepper motor with 1:5 ratio belt gears
24v DC power supply

I am reusing the existing CGE pro 9pin din, so i will be adding a boards for a cable harness at the controller and in the motor enclosures. 

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