Erik Madsen asked 3 years ago
To scan a 16×32 led matrix I need a 6 bit parallel port for data, and a 3 bit parallel port for Addr. Is there anyway I can do that, or du I have to write one bit at a time ?
Erik
Gil Shultz answered 3 years ago
There are a lot of ways, but I cannot help at this point, what are you trying to do, light the LEDs one at time? It can be done with 5 74HCT595s via a SPI interface. How fast does this need to happen. Do the bits need to be latched? Do you need to read the data? I assume this is with a ESP device.
Erik Madsen answered 3 years ago
I am making a clock and the matrix used to show the time. On an other board. I update the matrix in an interrupt routine it is interruptet 500 times a secund, and every time I write to these ports 32 times on every interrupt. There is no need to latch ‘is done on the display’ and no need to read. I have made clocks that get time from 77,5khz time sender men it is getting more unstable som times there can go hours before I get a stable signal, now I will use the esp32 to get time from interne.
Gil Shultz answered 3 years ago
Sorry but I am at a loss. Your latches are on the display. A simple schematic would help, What do the outputs of the matrix look like? More information on the interface and what it is with preferably a link to technical info on it.
Erik Madsen answered 3 years ago
Take a look at this site you can se the display at its connection.
https://learn.adafruit.com/connecting-a-16×32-rgb-led-matrix-panel-to-a-raspberry-pi?view=all
You can see there is 12 connections, I need to connect to ESP32. But we are getting away from my fist ask. Can I make a setup so it is possible to write to 6 of these output (R1,G1,B1,R2,G2,B2) with one instruktion ?
Gil Shultz answered 3 years ago
Sorry I get a 404 error from your link. From what you are saying and as I understand it you need to put the data to the latches then strobe it. If that is correct it is not to hard. Also I am assuming you have to select the group. You could do it with 595’s cascaded. Going through the data sheet there is no parallel port. The Pi does have a data bus that is pinned out. From that you should be able to generate an address and data buss as it has the appropriate strobe capability. Although much faster the ESP also has that but it is not brought for general usage. If you want to do a parallel write and not use shift registers you will have to pick another microprocessor. This capability is generally on multi chip processors and not that common on single chip processors.
Erik Madsen answered 3 years ago
First off all thanks for trying to help, I hope I can get to work with write to one pit at a time.
Try to search for ‘adafruit 16×32 RGB LED matrix’I hope it will give some hints you ca see.