GorbaDisplay: Difference between revisions
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This thing consists of two main parts: | This thing consists of two main parts: | ||
* a control board | * a control board, with logic to receive (for example) text messages over a serial connection and convert them to a bitmap display on the display board | ||
* a LED | * a display board, with logic to light up each LED | ||
Between them is a 14-pin connector, probably carrying the low-level LED control signals. | Between them is a 14-pin connector, probably carrying the low-level LED control signals. | ||
The display board consists of several (4?) panels of LEDs. | |||
It has a light sensor to sense the ambient light level. | |||
=== Theory of operation === | |||
My guess this is probably another row-multiplexed display. | |||
The display can light up one row at a time. By quickly lighting up each row in succession, the illusion to a human observer is that all LEDs are on simultaneously. | |||
The display board contains the followings integrated cicruits: | |||
* 74HC541, an octal buffer/line driver, probably buffers all signals coming in from the 14-pin connector to the rest of the electroncis | |||
* 74HC238, a 3-to-8 line decoder/demultiplexer, probably selects which row is currently being lit up | |||
* group of 4x IRF7425, power MOSFET, probably drives a row of LEDs | |||
* a whole bunch of TPIC6C596, 8-bit shift register, probably drives the columns inside one row of LEDs | |||
=== 14-pin connector === | |||
My guess for the pinout so far is: | |||
== Software == | == Software == | ||
Revision as of 21:37, 1 August 2023
| Project GorbaDisplay | |
|---|---|
| File:Whyunopicture.jpg | |
| Public transport LED display | |
| Status | Initializing |
| Contact | bertrik, User:Eloy |
| Last Update | 2023-08-01 |
Introduction
This project is about reverse engineering a former public transport LED display. It consists of Z panels of each X*Y LEDs. Each panel has 16 amber LEDs vertically.
The plan is to make the display fully addressable as a bitmap display over a network connection, preferably with individually controllable brightness.
Hardware
This thing consists of two main parts:
- a control board, with logic to receive (for example) text messages over a serial connection and convert them to a bitmap display on the display board
- a display board, with logic to light up each LED
Between them is a 14-pin connector, probably carrying the low-level LED control signals.
The display board consists of several (4?) panels of LEDs.
It has a light sensor to sense the ambient light level.
Theory of operation
My guess this is probably another row-multiplexed display. The display can light up one row at a time. By quickly lighting up each row in succession, the illusion to a human observer is that all LEDs are on simultaneously.
The display board contains the followings integrated cicruits:
- 74HC541, an octal buffer/line driver, probably buffers all signals coming in from the 14-pin connector to the rest of the electroncis
- 74HC238, a 3-to-8 line decoder/demultiplexer, probably selects which row is currently being lit up
- group of 4x IRF7425, power MOSFET, probably drives a row of LEDs
- a whole bunch of TPIC6C596, 8-bit shift register, probably drives the columns inside one row of LEDs
14-pin connector
My guess for the pinout so far is: