3 ms·

Did you intentionally leave out Arduino from the "what to drive with" options?

tyingq 4y ago
Assuming largish, multi-color matrixes, and/or chained ones, yes. A ~10Mhz+ pixel clock, double-buffering, or just the size of the pixel map would strain most of those. This sign is 32x128 pixels, with each pixel taking data for RGB (on/off), with the PWM rate controlling brightness for each of the three colors. Though there are examples of using something beefier/faster like an ESP32. There's also in this case, the assumed requirement of fetching train data and transforming text into pixels. The panels themselves don't take data and hold it. You have to refresh the display constantly, typically on a 1/8 or 1/4 duty cycle. You can drive smallish, single color matrix displays with a cheap MCU. Or there's also the approach of using addressable LEDs instead of these more "dumb" matrix modules, like arranging the smart strips into a matrix. Moves the refresh logic down into each LED.
- spdustin 4y ago
  The ESP32 can handle a 64x64 HUB75 display pretty handily. Several of them, even. There’s a solid library out there [0] that just pumps pixels right from memory via the ESP32’s built-in DMA engine. Adafruit_GFX is the supported library for drawing primitives/text/bitmaps/etc., so you can re-use a lot of code that’s out there. But let’s start with a simple, quick hit of dopamine: There’s a web-based installer [1] (it uses web serial, so Chrome is required) for a couple varieties of clock designed for a 64x64 HUB75 panel and an ESP32. $20 in parts from AliExpress if you already have a suitable 5V power supply. To use that site, all you need is that aforementioned 5V power supply—4A or more recommended, 10A if you’re planning to drive a full panel of pixels on an outdoor panel at full brightness—a 64x64 HUB75 matrix panel, and an ESP32. Everything except power is run directly to the ESP32. Many panels even come with a 16-pin female IDC connector for the panel, with individual DuPont-style female connectors at the other end that you can just slip over the pins on the ESP32. The source code for each clock (repo is linked from the web page) is a great starting point for making your own versions. The panels, as others have mentioned, are shockingly cheap from the usual sources like eBay [2] or AliExpress (search for “HUB75 panel” or “p3 64x64”), but even those in a hurry can get a 64x64 panel for under $40 from Amazon [3]. [0]: https://github.com/mrfaptastic/ESP32-HUB75-MatrixPanel-DMA https://github.com/mrfaptastic/ESP32-HUB75-MatrixPanel-DMA [1]: https://clockwise.page https://clockwise.page [2]: https://www.ebay.com/sch/i.html?_nkw=HUB75%20Panel https://www.ebay.com/sch/i.html?_nkw=HUB75%20Panel [3]: https://www.amazon.com/dp/B0B3F7WKJ1/ https://www.amazon.com/dp/B0B3F7WKJ1/
  - tyingq 4y ago
    That is impressive, though it's using a few tricks to keep up, like relatively low-duty cycle panels, and BCM in place of PWM.
- seanw444 4y ago
  I see now.
- sircastor 4y ago
  Yeah. I tried a project driving 32x16 pixels with a Arduino (an Uno, ATMega328) and it was just barely on the edge of usable for mild animation. Furthermore, I could really only use it at full brightness. These panels are extremely bright, and my project was meant to be desktop display. For the next version, I moved to an ESP8266 which provides plenty of compute speed to drive these panels at a brightness that’s comfortable.

Assuming largish, multi-color matrixes, and/or chained ones, yes. A ~10Mhz+ pixel clock, double-buffering, or just the size of the pixel map would strain most of those. This sign is 32x128 pixels, with each pixel taking data for RGB (on/off), with the PWM rate controlling brightness for each of the three colors. Though there are examples of using something beefier/faster like an ESP32. There's also in this case, the assumed requirement of fetching train data and transforming text into pixels. The panels themselves don't take data and hold it. You have to refresh the display constantly, typically on a 1/8 or 1/4 duty cycle. You can drive smallish, single color matrix displays with a cheap MCU. Or there's also the approach of using addressable LEDs instead of these more "dumb" matrix modules, like arranging the smart strips into a matrix. Moves the refresh logic down into each LED.

spdustin 4y ago
The ESP32 can handle a 64x64 HUB75 display pretty handily. Several of them, even. There’s a solid library out there [0] that just pumps pixels right from memory via the ESP32’s built-in DMA engine. Adafruit_GFX is the supported library for drawing primitives/text/bitmaps/etc., so you can re-use a lot of code that’s out there. But let’s start with a simple, quick hit of dopamine: There’s a web-based installer [1] (it uses web serial, so Chrome is required) for a couple varieties of clock designed for a 64x64 HUB75 panel and an ESP32. $20 in parts from AliExpress if you already have a suitable 5V power supply. To use that site, all you need is that aforementioned 5V power supply—4A or more recommended, 10A if you’re planning to drive a full panel of pixels on an outdoor panel at full brightness—a 64x64 HUB75 matrix panel, and an ESP32. Everything except power is run directly to the ESP32. Many panels even come with a 16-pin female IDC connector for the panel, with individual DuPont-style female connectors at the other end that you can just slip over the pins on the ESP32. The source code for each clock (repo is linked from the web page) is a great starting point for making your own versions. The panels, as others have mentioned, are shockingly cheap from the usual sources like eBay [2] or AliExpress (search for “HUB75 panel” or “p3 64x64”), but even those in a hurry can get a 64x64 panel for under $40 from Amazon [3]. [0]: https://github.com/mrfaptastic/ESP32-HUB75-MatrixPanel-DMA https://github.com/mrfaptastic/ESP32-HUB75-MatrixPanel-DMA [1]: https://clockwise.page https://clockwise.page [2]: https://www.ebay.com/sch/i.html?_nkw=HUB75%20Panel https://www.ebay.com/sch/i.html?_nkw=HUB75%20Panel [3]: https://www.amazon.com/dp/B0B3F7WKJ1/ https://www.amazon.com/dp/B0B3F7WKJ1/
- tyingq 4y ago
  That is impressive, though it's using a few tricks to keep up, like relatively low-duty cycle panels, and BCM in place of PWM.
seanw444 4y ago
I see now.
sircastor 4y ago
Yeah. I tried a project driving 32x16 pixels with a Arduino (an Uno, ATMega328) and it was just barely on the edge of usable for mild animation. Furthermore, I could really only use it at full brightness. These panels are extremely bright, and my project was meant to be desktop display. For the next version, I moved to an ESP8266 which provides plenty of compute speed to drive these panels at a brightness that’s comfortable.