HCS08LG32 Pin Multiplex Question

[Thunder]

Hi, I'm using the LG32 and wish to use GPIO pins as full complementary driver.  According to the LG32 manual:

 "Pins that have shared function with the LCD have special behavior based on the state of the VSUPPLY bits in the LCDSUPPLY register. These pins (PTA, PTB, PTC[4:0], PTD, PTE and PTG) can operate as full complementary drive or open drain drive depending on the VSUPPLY bits. When VLL3 is connected to VDD externally, VSUPPLY = 11, FCDEN = 1, and RVEN = 0; the pins operate as full complementary drive. For all other VSUPPLY modes, the GPIO shared with LCD operates as open drain. "

My problem is that I am unable to change the VSUPPLY to 11 or FCDEN to 1 (RVEN=0 by default).  When attempting to change these values in CodeWarrior using the memory window, my new values are not accepted.  I also cannot change the values in code.  I have also tried jumpering VLL3 to VDD externally and re-booting the board....still no success.

Any suggestions welcome.

[Oliver · Accepted solution]

Hi,

you need to disable clock gating for the LCD module e.g. like this:

SCGC2_LCD = 1;

otherwise there are no clocks to the module and some registers don't work correctly.

Best regards,

Oliver

[Thunder]

Thanks Oliver. In the interim I contacted Freescale support, who pretty much said the same thing.  I used their input and it is working fine now.  FYI, I am enclosing below their response which helped me through this...

 /** Enable clock to the LCD module */

 SCGC2_LCD = 1;

/** Disable LCD module */

LCDC0_LCDEN = 0;

LCDC1_FCDEN = 1;

LCDSUPPLY_VSUPPLY = 0b11;

"The most common error that I've seen so far is that the first two lines aren't included. These instructions are very important because if the module doesn't have a bus clock enable, the registers will not experience any change. In order to have a better configuration the LCD peripheral needs to disable the waveform generation (second instruction) "