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• The parts arrive and the fun begins

  seasleyece • 02/07/2023 at 00:06 • 0 comments

  The PWBs and parts have almost all arrived.  There will be 3800+ parts and easily 15k+ solder joints. Seemed like a good idea at the time.....

• Day2'ish - Design Electrical

  seasleyece • 01/30/2023 at 20:21 • 0 comments

  The display controller is based on the version that I used in my V1 matrix.  Biggest difference is that I dropped the RF module that I will never get around to doing anything with and increased the HUB75 drives from 2 chains to 4 chains.  Image of the layout is below.

  The display boards are 4x the size of the V1 matrix holding a total of 32 quad even segment displays. Each Display board has a HUB75'ish display input.  The biggest difference is that there are two sets of 4-bit outputs rather then the HUB75 two 3-bit outputs.  The bits are shifted between the input and output connector.  i.e. input bit 1 goes to output bit 0 and so one.  This allows for all 4 panels in each chain to be updated at the same time.  This greatly reduces the clock speed needed to get the panels updated.  The segments are being drive at a 1/16th duty cycle.  This means that only 1/16 of the digits are one at any one time.  This is common with HUB75 based displays. An image of the Display board PWB is below.  For size comparison the actual board will be 8" by 7.8" or 202.69 mm* 157.12 mm in units that the rest of the world uses.

  Here is a pretty rendering of the module done in OnShape.

  Putting all 16 modules in we get a display that is 32"x24.7" with 32k+ pixels.

• Day 1'ish

  seasleyece • 01/30/2023 at 19:51 • 0 comments

  The display will consist of 16 display boards that each hold 32 quad seven segment displays and all needed driver circuits.  The display boards will use a HUB75'ish style control but with the data lines paralleled for lower clock scan rates.  This means that all 16 boards are updated at the same time so there is no performance degradation for making the display bigger.

  Originally I started off with a simulator based on the Seven Segment Sign SSS Documentation.  It is written in Python and has some real performance issues.  After realizing that was not going to work I went back to the original simulation I made for the V1 display and ported it over to use CodeBlocks with the MingGW compiler and OpenGL.  The same build works both on a WIndows PC and the PI with only changing the version of GLUT being used.  Will eventually get the code on GitHub as I would like to see if anyone wants to help create animations or anything else for the display.

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