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Is it Possible to use VLCD input to measure without enabling LCDEN in LCD register?

Associate II


I'm using an L073Rz.

I was wondering if it was possible to use the VLCD as a measurement pin by using the ADC channel reserved for it, without enabling any LCD pin (for communication) and functionalities.

LCD_CR->LCDEN = 0; (lcd controller disabled)

LCD_CR->VSEL = 1; (setting the external source, so VLCD act as an input)

ADC_CCR->VLCDEN = 1; (reading circuitry enabled)

The LCD clock enable seems also mandatory.

Through Cube MX it seems not possible as is, you have to enable LCD in order to get VLCD measurement in ADC.

If I modify it myself should I be getting the possibility to do what i'm looking for.

Best Regards,


Uwe Bonnes
Principal II

You can monitor that line without LCD enabled, but the voltage will not be active as the LCD voltage generation is not active with the LCD inactive. Wht do you really intend to do?

Associate II

I'm not using any LCD in my project I just want to use it as an external tension monitoring.

I read in the reference manual that VLCD pin is routed through a bridge divider, I'm trying to use this bridge in order to make a tension measurement.

I don't need this tension to be send though another pin as what seems to be the regular usage of VLCD.

Because the bridge is internal and piloted with soft I won't have to add an external bridge and command, it will save me some space on the PCB.

I'm going for the minimum settings to enable the measurement and activate bridge ratio.

Associate II

Through testing it seems to be working.

I'm sending sending a tension equal to Vref, my ADC value is stuck to it's maximum,but the bias selection (in LCD register) doesn't seems to change anything to the value I get.