STM32L1xxx VLCD (step up converter configuration )

[moran]

Posted on November 27, 2014 at 10:55

Hi,

I want to connect LCD to the ST using VLCD pin , but instead of 3V i need 4.5 V.

I found in data sheet that there is stepup converter (kind of SW configurable DC2DC)  that can be used for this purpose but i couldn't find any other information - how to handle it by software.

1) is it correct ?

2) if yes, how to configure it.

Thanks in advance ,

Moran.

 

#lcd #stm32l1 #vlcd

[waclawek.jan]

Posted on November 28, 2014 at 11:13

> I want to connect LCD to the ST using VLCD pin , but instead of 3V i need 4.5 V.

You can't. The maximum voltage on VLCD pin is 3.6V.

> I found in data sheet that there is stepup converter (kind of SW configurable DC2DC)  that

> can be used for this purpose but i couldn't find any other information - how to handle it by

> software.

All the information you need is in RM0038 and the datasheet. The steupup is switched on by clearing VSEL bit in LCD_CR and its output controlled by CC[2:0] bits in LCD_FCR; in that case you need to have a capacitor connected to VLCD instead of external voltage source. But don't hope for output higher than 3.6V - this chip is simply not capable of handling higher voltages.

You'll need to use the LCD accordingly.

JW

 

[moran]

Posted on November 30, 2014 at 09:27

Thanks alot JW.

I've read the reference but couldn't understand what should I do if I need  4.5V instead of maximum 3.6V for better contrast.