Friday, October 7, 2011

Difference between 3208 and 0832 LED displays from Sure Electronics

Many people are building stuff using the 3208 LED display from Sure, based on projects I have shown here (e.g. BookClock). The test code I published doesn't work "out of the box" with these newer displays. So they ask the question: why? Here is the answer.

The "older" 0832 LED display uses the HT1632 chip. The "newer" 3208 (which comes with either 3mm or 5mm LEDs) uses the slightly different HT1632C chip. (Note that HT1632C chip is also used in the bi-color 3216 displays.)
The difference between these two chips, from the software perspective, is in the initialization procedure.

Here is part of the ht1632_setup() function for the 0832 display (with HT1632):

  ht1632_sendcmd(HT1632_CMD_SYSDIS);  // Disable system
  ht1632_sendcmd(HT1632_CMD_COMS10);  // PMOS drivers
  ht1632_sendcmd(HT1632_CMD_MSTMD); // Master Mode
  ht1632_sendcmd(HT1632_CMD_SYSON); // System on
  ht1632_sendcmd(HT1632_CMD_LEDON); // LEDs on

And here is the similar code for the 3208 display (both the 3mm and 5mm versions, only the LED matrices are different) with HT1632C:

    ht1632_sendcmd(HT1632_CMD_SYSDIS);  // Disable system
    ht1632_sendcmd(HT1632_CMD_MSTMD); /* Master Mode */
    ht1632_sendcmd(HT1632_CMD_RCCLK);  // HT1632C
    ht1632_sendcmd(HT1632_CMD_SYSON); /* System on */
    ht1632_sendcmd(HT1632_CMD_LEDON); /* LEDs on */

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