Radio Module Problem

[abdullahseba]

can any one tell me what this means? In the datasheet attached it says on page 5 it said that pin 7 was not to be connected to a VDD or high level of CMOS output. Does that mean you cannot connect it directly to a micro-controller or does it mean something else?

[AndyC_772]

It probably means it's a logic input for which logic '1' is a lower voltage than the supply voltage for the module, and which would be damaged if the full supply voltage were to be applied.

If you can configure a microcontroller pin to always either output a logic '0' or be a high impedance input (without pull-up or pull-down), then that would probably work OK. There's a risk, though, that you don't always know what the pin will do during power-up or down, or during programming, or in the time in between being powered up and reaching the part of your code which configures it.

The safe thing to do is to use an external FET, like, say, a 2N7002, to pull the pin to GND, and to drive the gate of that FET with the microcontroller's output. You then just need to configure the MCU pin as an output, and nothing it does can cause the pin of the radio module to be driven high.

[abdullahseba]

It probably means it's a logic input for which logic '1' is a lower voltage than the supply voltage for the module, and which would be damaged if the full supply voltage were to be applied.

If you can configure a microcontroller pin to always either output a logic '0' or be a high impedance input (without pull-up or pull-down), then that would probably work OK. There's a risk, though, that you don't always know what the pin will do during power-up or down, or during programming, or in the time in between being powered up and reaching the part of your code which configures it.

The safe thing to do is to use an external FET, like, say, a 2N7002, to pull the pin to GND, and to drive the gate of that FET with the microcontroller's output. You then just need to configure the MCU pin as an output, and nothing it does can cause the pin of the radio module to be driven high.

Thanks