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| Arduino as SPI slave with output to LCD? |
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| degreelessengineer:
I have been working on a Nikon flash which suffered a TAB bonding failure on the main lcd panel. I have been unable to locate an original LCD panel and have been connecting up various SPI displays of a similar resolution to try and get it working to no avail. I know the original pinout for the SPI communication and can see data coming from it. I am wondering if it would be possible to use an Arduino to read the SPI data and store the data into a variable. I have another working flash that I can read SPI data from and compare with what is displayed on screen. Using the second working flash, I would like to compile a list of SPI data that corresponds to what is displayed on the screen and output it to a standard LCD panel. Would this be possible with an Arduino? |
| Zapro:
Should be doable :) If you can find a service manual for the flash, it might contain some hint on the communication on the display. // Per. |
| mikerj:
Note that SPI is a time critical protocol, unlike I2C the slave has no means of making the master device wait for it to process incoming or outgoing data. Depending on the clock speed this can be problematic when a master gives little turn around time e.g. the master sends a register address to to read and expects the slave to send the first bit of data on the next SCK clock cycle. Small, fast low latency SPI interrupt handlers on the slave are the order of the day. |
| madires:
For a low SPI clock rate it might work. But the main task is to figure out the LCD controller by looking at the commands sent. If you know the LCD controller you'll possibly find a matching display. |
| jpanhalt:
When you read the SPI from the good device, what are the characters? Is it 8-bit or 16-bit ( 2 sequential 8 bits). That is, are the characters just ASCII values (seems unlikely), a mixture of ASCII characters and commands, or values that you cannot interpret. You will need to separate screen navigation commands from characters, and if the Nikon screen was specially designed (i.e., has preset characters) you will have a lot of decoding to do. Is the Nikon screen a character screen or graphical screen? By graphical, I mean can individual pixels or bytes of pixels be addressed? I would start with deciphering the data from the good screen. SPI is an easy protocol to use (it just swaps bits) and can work down almost to DC, so that by itself should not be a hurdle. |
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