CCS/MSP430F6736: Problem in lcd module

Hello,

Thank you for your detailed post. I suspect that the solution here is selecting the correct LCDMx bits for desired characters.

To get started, refer to the VIM-828-DP13.2-RC-S-LV datasheet where the LCD memory map is provided (shown below).

Next, refer to Figure 35-2 in the MSP430F6736 User's Guide where the LCD memory map is provided for 4-mux mode for (less than or equal to) 160 segments (shown below). Notice that this table is just transposed compared to the VIM-828 table.

Now, let's display a "0" on character 6. Looking at the LCD memory map for the VIM-828, you'll want segments 6A, 6B, 6C, 6D, 6E, and 6F. These segments correspond to Pins 24 and 12. Looking at the MSP430F6736 LCD memory map, these pins correspond to the lower four bits in the registers LCDM13 and LCDM7.

// Print a zero on Character 6

LCDM7 = BIT1 | BIT2 | BIT3;     // COM1, COM2, COM3
LCDM13 = BIT0 | BIT1 | BIT2;   // COM0, COM1, COM2

For more information about how LCD's work, please refer to our Designing With MSP430™ MCUs and Segment LCDs application report.

Hope this helps!

Regards,

James

MSP Customer Applications

Hi James,
Thanks for your great support.The details where correct as per you shown but it's not the right thing for me .i explain in detail
in my design com0,com1,com2 and com3 where connected to the lcd modules pin19,pin36,pin18,pin1 .
and from my observation LCDM1 and LCDM16 for first position
LCDM2 and LCDM15 for second position and correspondingly.
because starting s0 in pin2  of lcd and s31 in pin 35 . and the idea get from user guide page 922.(pin 2 ,pin3 and pin34,pin 35 for first position ,the corresponding pins in mcu s0,s1 and s30, s31 so from the page 922 s0, s1 memmory reg is LCDM1 and s30, s31 memmory reg is LCDM16)
on this way i print characters in every positions and works great but when i put a value in the 6 th and 7th position the lcd will not work properly some times the other field characters disappeared or some wrong lines where open.I doubted two things either lcd is damaged or my configuration is wrong .I need an expert opinion that's why i ask you .please solve it properly .

Aju.S

I would highly recommend carefully reading through Section 5 LCD Layout and Software Considerations in the previously-mentioned Designing With MSP430™ MCUs and Segment LCDs application report. It's a helpful reference for mapping the LCD pins to the MCU and also hardware and software layout considerations.

I suspect that if you follow the guidelines in Section 5, you'll resolve your issue.

Regards,

James

MSP Customer Applications

Hi james,

thanks for your valuable support ,i attached my board's schematics here (for LCD only).Please verify  and support me to correct the issue.

Hello,

Thanks for sharing your schematic. The connections seem correct as long as you realize that your pins (and therefore your LCD memory map) are shifted by two or four relative to your Sx connections. For example, S0 is connected to Pin 2, S1 to Pin 3, etc. (difference of 2), but then S16 is connected to Pin 20, S17 to Pin 21, etc. (difference of 4 now). You'll need to account for this when using the LCDMx registers.

In my code above where I was using LCDM7 and LCDM13, I was assuming that you connected S2 to Pin 2, S3 to Pin 3, etc., so you'll need to change this accordingly. I suspect that the issue comes down to mapping the pins to the segments and understanding the offsets.

Regards,

James

MSP Customer Applications

Hello,

Thanks for the helpful summary. Looking at everything, your LCD/MCU connections and register configurations all seem fine and mapped correctly. With this confirmed, let's move on.

Next, I took a look at the erratasheet for the MSP430F6736 and discovered there are two LCD related errata, LCDB5 and LCDB6. Please take a look at both of these below.

For the issue that you're observing, I suspect that LCDB6 is causing the issue. Per its workaround, it says "do not modify VLCDx and/or LCDCPEN bits in LCDCVCTL register while LCDON = '1' ". Looking at the code in your initial post, I see that LCDCVCTL is getting modified when LCDON = '1'. According to the Description, this could cause corrupted LCD output. Please implement this workaround and let me know if it resolves this issue before proceeding.

Regards,

James

MSP Customer Applications