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LP5521 LED driver loading question

Andy Hsu
Prodigy 170 points
Other Parts Discussed in Thread: LP5521

Dear All, 

I am trying LP5521 LED driver, there is no any problem on DIRECT mode, and load flash pattern one time then execute.  

but if  I am trying to load different patterns and run. It will be very unstable. 

Repeat loading/execute seems to easy be fail. Sometimes it can display right pattern, sometimes go bad, or display a strange pattern.

Does loading just can do only one time after power on?

(commands pattern has no problem, and have enough wait delay for OP_MODE/ENABLE registers writing)

Already try many ways but can't find a rule. 

Does any one have same experience? Thanks very much. 

p.s. I've seen a code on the WEB shows below, is there any problem on IC?

 /*
299          * Make sure that the chip is reset by reading back the r channel
300          * current reg. This is dummy read is required on some platforms -
301          * otherwise further access to the R G B channels in the
302          * LP5521_REG_ENABLE register will not have any effect - strange!
  • 0
    TI__Intellectual 2510 points

    Hi Sheng-Ping,

    When you are loading different patterns, do you write the whole SRAM or just the size of your pattern? If there is some 'leftover' code from previous pattern it might cause issues.

    To avoid this you could use the END command or the GO TO START command or write '00' to the rest of the SRAM that is not used.

    Also note that when entering LOAD mode you need to be in DISABLED mode. So entering LOAD mode from RUN mode is not allowed.

    Thank you,

    Sami

  • 0 in reply to Sami Kotijarvi
    Prodigy 170 points

    Hi Sami, 

    Thanks very much for your support. 

    1. I always do "Entering LOAD mode after HOLD/DISABLED", it should be OK.

    2. I didn't write whole SRAM because the last command is END, and I've tried filling 0, but It seems still has problem.   

    3. I am trying to LOAD data to SRAM, then read back from it to check, the strange thing is that loaded data "sometimes " will shift one byte, and got display fail.

    For example:

    write and read back from SRAM(as same as loaded, display well):

    A0 87 0D 7F ...

     write and read back from SRAM(loaded data shift one byte, and display fail)

     00 A0 87 0D 7F ...

    Thanks,

    Andy

     

     

  • 0 in reply to Andy Hsu
    TI__Genius 11020 points

    Hi Andy,

    Have you checked/reset the program counter value (PC) when you start the execution again? Maybe the PC is not where it should be and it is making the new sequence to behave erratic.

    Thanks.

    -Tomi