IoT For Makers

A few days ago, an order from Aliexpress arrived. This product is often used in commercial LED signboards. The product name is HD-D15 (HD-D10) Full color LED display Video Control card. HD-D15 asynchronous Full color LED display Video Control card <HD-D15 Video Control Card> There are two types of products that support WiFi and only Ethernet. The specifications of these products are as follows. Note the part D15 on the left side of the figure. A brief summary of the features follows. Four HUB75 interfaces are provided. Therefore, four daisy chains can be made at the same time.  10 units can be connected in one chain based on 32X64 LED Matrix and a total of 40 units can be connected. It has 4GB of memory and the CPU is a Quadcore 64bit Rockchip px30. The display quality is excellent because it is an LED Matrix exclusive product. You can use HDPlayer, a content authoring tool. Download and Install the HDPlayer First, download HDPlayer from the follo...

So far I've only used one chain to handle the RGB LED matrix on the Raspberry Pi. Adafruit's HAT and Bonnet only support one chain. <Adafruit HAT/Bonnet that supports one HUB75 interface> However, the PCB designed by Henner Zeller supports up to three chains. This is the maximum number of chains that the Raspberry Pi's 40 GPIO can support. <Henner Zeller's HAT and Electrodragon HAT those support 3 chains> Why use multi chains Use daisy connections to connect multiple LED matrices in a chain. I've explained daisy connectin in my other blog . Daisy connections are not infinitely possible. Since the signal must be delivered to adjacent LEDs, connecting more than a certain number will slow down the signal transmission and cause screen flicker. Henner Zeller recommends no more than 12 connections in a chain. However, this value depends on which LED matrix, Raspberry Pi you use. For example, using a 64X64 LED matrix will reduce the nu...

This post is related to several posts written to use the RGB LED matrix in Raspberry Pi. If you haven't read the previous posts, it can be hard to understand, in which case you ㅡmight read the previous posts in advance. I've covered in previous post that Rasbian Buster and the RGB Matrix HAT don't fit together. I was able to play the video successfully. However, noise often appeared on the video screen. To solve this problem, I have tried various things such as changing the power and changing the video format, testing various Raspberry Pi models(2B,3B,4B) but I could not improve it. Clues to solving this problem can be found on Henner Zeller's git page . If you read the Troubleshooting section, there is a description of the brightness instability in the latest version of Rasbian, and introduces issue # 483 . This is due to a structural problem in the latest Raspbian kernel. In the contents, the 2016 Jessie version says there are very few problems. So I de...