GorbaDisplay - Revision history

Bertrik Sikken: /* Theory of operation */

2023-09-19T10:47:19Z

Theory of operation

← Older revision		Revision as of 10:47, 19 September 2023
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	=== Theory of operation ===		=== Theory of operation ===
	This is a row-multiplexed display, during each phase it lights up 1/4th of its rows.		This is a row-multiplexed display, during each phase it lights up 1/4th of its rows.
	By quickly lighting up ~~each row~~ in succession, the illusion to a human observer is that all LEDs are controlled simultaneously.		By quickly lighting up rows in succession, the illusion to a human observer is that all LEDs are controlled simultaneously.

	Each 32x16 panel contains 512 LEDs and 16x8-bit shift registers.		Each 32x16 panel contains 512 LEDs and 16x8-bit shift registers.

Bertrik Sikken: /* Software */

2023-08-16T08:21:59Z

Software

← Older revision		Revision as of 08:21, 16 August 2023
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	== Software ==		== Software ==
	Repository: https://github.com/bertrik/GorbaDisplay		Repository: https://github.com/bertrik/GorbaDisplay

			This is able to control one panel of 32x16 pixels using an ESP8266 (wemos d1 mini).

			Nice looking font for use on one panel:
			https://fontstruct.com/fontstructions/show/2168506/4x6-font-6
			Digits are 4 pixels wide, so should be able to fit an ip address on one panel (on two rows).

Bertrik Sikken: /* Theory of operation */

2023-08-13T10:11:32Z

Theory of operation

← Older revision		Revision as of 10:11, 13 August 2023
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	=== Theory of operation ===		=== Theory of operation ===
	This is ~~probably~~ a row-multiplexed display.		This is a row-multiplexed display, during each phase it lights up 1/4th of its rows.
			By quickly lighting up each row in succession, the illusion to a human observer is that all LEDs are controlled simultaneously.

	Each 32x16 panel contains 512 LEDs and 16x8-bit shift registers.		Each 32x16 panel contains 512 LEDs and 16x8-bit shift registers.
	~~Multiplexing is therefore probably 1-in-4.~~

	~~A panel can light up four rows at a time. By quickly lighting up each row in succession, the illusion to a human observer is that all LEDs are controlled simultaneously.~~

	==== row demultiplexer ====		==== row demultiplexer ====
	The demultiplexer ~~is capable of handling~~ 3 bits~~, enough~~ for ~~8 rows~~.		The row demultiplexer receives 3 bits input.
			The lower two bits are used to select which row (out of 4) to light up.
			The highest bit is used an enable bit for the row multiplexer.

	==== column registers ====		==== column registers ====
Line 50:		Line 50:
	It has a shift register consisting of 16 TPIC6C596 circuits organised in 4 rows of each 32 pixels. The shift registers of one panel are wired up in series.		It has a shift register consisting of 16 TPIC6C596 circuits organised in 4 rows of each 32 pixels. The shift registers of one panel are wired up in series.
	At the end of the shift register chain of each panel, there is another 596 chip, the output feeds into the data pin of the output 14-pin connector.		At the end of the shift register chain of each panel, there is another 596 chip, the output feeds into the data pin of the output 14-pin connector.

	~~Possibly one out of four rows can be lit at a time this way.~~

	=== 14-pin connector ===		=== 14-pin connector ===

Bertrik Sikken: /* Introduction */

2023-08-13T10:05:21Z

Introduction

← Older revision		Revision as of 10:05, 13 August 2023
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	== Introduction ==		== Introduction ==
	This project is about reverse engineering a former public transport LED display.		This project is about reverse engineering a former public transport LED display.
	It consists of Z panels of each X * 16 LEDs.		It consists of 4 panels of each 32 * 16 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 per pixel.		The plan is to make the display fully addressable as a bitmap display over a network connection, preferably with individually controllable brightness per pixel.

	~~TODO:~~
	* more reverse engineering by tracing out the connector to the individual lines of the integrated circuits -> mostly done now
	* is there a separate power supply line to the board? if so, can we power our new microcontroller from the 14-pin connector? -> NO appears to be only 2.2V!
	* measure clock frequencies (column clock, line update frequency) of original controller board
	* write software to control this thing, e.g. for ESP8266
	* investigate https://github.com/qisun1/ESP8266_LED_64x16_Matrix , seems to be a similar display

	== Hardware ==		== Hardware ==

Bertrik Sikken: /* 14-pin connector */

2023-08-12T20:10:07Z

14-pin connector

← Older revision		Revision as of 20:10, 12 August 2023
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	=== 14-pin connector ===		=== 14-pin connector ===
	~~My guess~~ for the pinout ~~so far is~~:		Connections for the pinout are:
	{\| class="wikitable"		{\| class="wikitable"
	\|+Connections		\|+Connections

Bertrik Sikken: /* 14-pin connector */

2023-08-12T20:09:37Z

14-pin connector

← Older revision		Revision as of 20:09, 12 August 2023
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	\|+Connections		\|+Connections
	\|-		\|-
	!Pin!!Id!!Remark		!Pin!!Id!!Wemos D1 mini!!Remark
	\|-		\|-
	\|1\|\|VCC\|\|Power		\|1\|\|VCC\|\|-\|\|Power
	\|-		\|-
	\|2\|\|VCC\|\|Power		\|2\|\|VCC\|\|-\|\|Power
	\|-		\|-
	\|3\|\|ROW_SEL0\|\|74HCT541:A3-Y3 -> 74HCT238:A0, 0 = active		\|3\|\|ROW_SEL0\|\|D1\|\|74HCT541:A3-Y3 -> 74HCT238:A0, 0 = active
	\|-		\|-
	\|4\|\|ROW_SEL1\|\|74HCT541:A2-Y2 -> 74HCT238:A1, 0 = active		\|4\|\|ROW_SEL1\|\|D2\|\|74HCT541:A2-Y2 -> 74HCT238:A1, 0 = active
	\|-		\|-
	\|5\|\|ROW_SEL2\|\|74HCT541:A1-Y1 -> 74HCT238:A2, acts as a disable for the row multiplexer		\|5\|\|ROW_SEL2\|\|D3\|\|74HCT541:A1-Y1 -> 74HCT238:A2, acts as a disable for the row multiplexer
	\|-		\|-
	\|6\|\|?\|\|74HCT541:A0-Y0 -> ?		\|6\|\|?\|\|-\|\|74HCT541:A0-Y0 -> ?
	\|-		\|-
	\|7\|\|?\|\|		\|7\|\|?\|\|-\|\|
	\|-		\|-
	\|8\|\|?\|\|		\|8\|\|?\|\|-\|\|
	\|-		\|-
	\|9\|\|COL_DATA\|\|596:SER_IN		\|9\|\|COL_DATA\|\|D5\|\|596:SER_IN
	\|-		\|-
	\|10\|\|COL_ENABLE\|\|74HCT541:A4-Y4 -> 596:G, 0 = active, 1 = inactive		\|10\|\|COL_ENABLE\|\|D6\|\|74HCT541:A4-Y4 -> 596:G, 0 = active, 1 = inactive
	\|-		\|-
	\|11\|\|COL_CLOCK\|\|74HCT541:A5-Y5 -> 596:SRCK		\|11\|\|COL_CLOCK\|\|D7\|\|74HCT541:A5-Y5 -> 596:SRCK
	\|-		\|-
	\|12\|\|COL_LATCH\|\|75HCT541:A6-Y6 -> 596:RCK		\|12\|\|COL_LATCH\|\|D8\|\|75HCT541:A6-Y6 -> 596:RCK
	\|-		\|-
	\|13\|\|GND\|\|~~Power~~		\|13\|\|GND\|\|GND\|\|Ground
	\|-		\|-
	\|14\|\|GND\|\|~~Power~~		\|14\|\|GND\|\|-\|\|Ground
	\|}		\|}

	== Software ==		== Software ==
	Repository: https://github.com/bertrik/GorbaDisplay		Repository: https://github.com/bertrik/GorbaDisplay

Bertrik Sikken: /* 14-pin connector */

2023-08-12T19:09:58Z

14-pin connector

← Older revision		Revision as of 19:09, 12 August 2023
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	\|2\|\|VCC\|\|Power		\|2\|\|VCC\|\|Power
	\|-		\|-
	\|3\|\|ROW_SEL0\|\|74HCT541:A3-Y3 -> 74HCT238:A0		\|3\|\|ROW_SEL0\|\|74HCT541:A3-Y3 -> 74HCT238:A0, 0 = active
	\|-		\|-
	\|4\|\|ROW_SEL1\|\|74HCT541:A2-Y2 -> 74HCT238:A1		\|4\|\|ROW_SEL1\|\|74HCT541:A2-Y2 -> 74HCT238:A1, 0 = active
	\|-		\|-
	\|5\|\|ROW_SEL2\|\|74HCT541:A1-Y1 -> 74HCT238:A2		\|5\|\|ROW_SEL2\|\|74HCT541:A1-Y1 -> 74HCT238:A2, acts as a disable for the row multiplexer
	\|-		\|-
	\|6\|\|?\|\|74HCT541:A0-Y0 -> ?		\|6\|\|?\|\|74HCT541:A0-Y0 -> ?

Bertrik Sikken: /* 14-pin connector */

2023-08-12T13:46:27Z

14-pin connector

← Older revision		Revision as of 13:46, 12 August 2023
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	\|9\|\|COL_DATA\|\|596:SER_IN		\|9\|\|COL_DATA\|\|596:SER_IN
	\|-		\|-
	\|10\|\|COL_ENABLE\|\|74HCT541:A4-Y4 -> 596:G		\|10\|\|COL_ENABLE\|\|74HCT541:A4-Y4 -> 596:G, 0 = active, 1 = inactive
	\|-		\|-
	\|11\|\|COL_CLOCK\|\|74HCT541:A5-Y5 -> 596:SRCK		\|11\|\|COL_CLOCK\|\|74HCT541:A5-Y5 -> 596:SRCK

Bertrik Sikken: /* 14-pin connector */

2023-08-12T13:36:27Z

14-pin connector

← Older revision		Revision as of 13:36, 12 August 2023
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	!Pin!!Id!!Remark		!Pin!!Id!!Remark
	\|-		\|-
	\|1\|\|~~GND~~\|\|~~Ground~~		\|1\|\|VCC\|\|Power
	\|-		\|-
	\|2\|\|~~GND~~\|\|~~Ground~~		\|2\|\|VCC\|\|Power
	\|-		\|-
	\|3\|\|ROW_SEL0\|\|74HCT541:A3-Y3 -> 74HCT238:A0		\|3\|\|ROW_SEL0\|\|74HCT541:A3-Y3 -> 74HCT238:A0
Line 92:		Line 92:
	\|12\|\|COL_LATCH\|\|75HCT541:A6-Y6 -> 596:RCK		\|12\|\|COL_LATCH\|\|75HCT541:A6-Y6 -> 596:RCK
	\|-		\|-
	\|13\|\|~~VCC~~\|\|Power~~, about 2.2V~~		\|13\|\|GND\|\|Power
	\|-		\|-
	\|14\|\|~~VCC~~\|\|Power		\|14\|\|GND\|\|Power
	\|}		\|}

	== Software ==		== Software ==
	Repository: https://github.com/bertrik/GorbaDisplay		Repository: https://github.com/bertrik/GorbaDisplay

Bertrik Sikken: /* Hardware */

2023-08-10T17:07:15Z

Hardware

← Older revision		Revision as of 17:07, 10 August 2023
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	* group of 4x IRF7425, power MOSFET, probably for driving a 1-out-of-4 row of LEDs		* group of 4x IRF7425, power MOSFET, probably for driving a 1-out-of-4 row of LEDs
	* a whole bunch of TPIC6C596, 8-bit shift register, probably drives the columns inside one row of LEDs		* a whole bunch of TPIC6C596, 8-bit shift register, probably drives the columns inside one row of LEDs
			* LMC6482, dual opamp, probably used to interface with the light sensor / LDR

	Each LED has a 10 ohm resistor in series. LEDs are amber/orange.		Each LED has a 10 ohm resistor in series. LEDs are amber/orange.