Config pin on RF module

M

manie

Senior Member
I have a PCB mounted 14-pin module. The Config pin requires to be pulled LOW in order to configure the module via serial comms. See below:
These pins control the module.The FORCE9600 pin, if pulled low, will force the serial interface to a baudrate of 9600.Releasing the FORCE9600 pin will allow the module to use the saved baudrate. The FORCE9600 pin will be obeyed at all times, regardless of the status of the CONFIG pin. The CONFIG pin, if pulled low, places the module in configuration mode, and allows the RF parameters to be updated via the serial interface. If the baudrate is changed during configuration, and FORCE9600 is not active, then the new baudrate will be active after the parameters have been saved using the 'X' command.These pins have internal pull-ups. Ideally, these pins should be driven from an open-collector output. If these pins are connected to a 5v-powered host, it is important that the host never drives 5v signals into these pins. The host should pull the line low, or leave the pin in a high-impedance state to be pulled high internally.
Click to expand...
The question is, how do I use the 28x1 and software to control this ? I've looked at manual 2 (input/output/low/high commands etc.) but I don't see how to do this AND prevent the Axe pin going high accidentally.

The way I see it is to drive a small NPN tranny to pull the line low to 0V. Am I correct ?
 
M

MartinM57

Moderator
manie said:
Ideally, these pins should be driven from an open-collector output...

The way I see it is to drive a small NPN tranny to pull the line low to 0V. Am I correct ?
Click to expand...
That would be a good solution i.e. the same way that a darlington transistor/array is used to power LEDs/motors etc. But you don't need the high gain/high power that a darlington gives, so a simple NPN (4k7 resistor between PICASE and base) would be fine. Just connect the collector to the FORCE9600 pin (and nowhere else!)
 
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