Intelligent Relay Bypass (early rev without Channel Switching)

benny_profane

Well-known member
What is the 47k resistor on the earlier rev of the board doing? It seems like that's the only circuit difference (beside the addition of the channel switching functionality in the newer boards). Also, what is the approximate voltage output and current limit for pin 5? I'd like to drive an LED indicator from that, but I wanted to check to see if making an LED daughterboard and using the NPN switch would be a better way to go.
 
The 47K was a pull-up resistor for the footswitch. It's no longer needed since enabling the internal pull-up resistor of the microcontroller.

Pin 5 is 5V high, maximum output current is 40mA.

You can drive an LED from the microcontroller directly with no problem. The transistor is used in the Intelligent PCB to sink current from the main effect PCB.
 
The 47K was a pull-up resistor for the footswitch. It's no longer needed since enabling the internal pull-up resistor of the microcontroller.
Did something change with the uC code? If so, does that mean that uCs shipped with the old rev of the board should still use the pull-up resistor?
 
Yes there was a code change.

There was a brief transition period where the code was updated ahead of the PCBs (the newer microcontroller is backwards compatible with the older board, but not the other way around)

You can power up the IC and measure Pin 5, if you measure 5V the internal pull-up is enabled and no external resistor is needed.
 
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