Waveshare 2.9" ePaper display Custom Chip

• chip data sheet

The WS29v2 Custom Chip simulates the Waveshare 2.9" (V2) ePaper display module.

The chip has the following pins:

Pin	Name	Description
1	BUSY	Busy state output pin Note 1.5-4
2	RST	# Reset Note 1.5-3
3	DC	Data /Command control pin Note 1.5-2
4	CS	# Chip Select input pin Note 1.5-1
5	CLK	serial clock pin (SPI)
6	DIN	serial data pin (SPI)
7	VCC	Power for interface logic pins
8	GND	Ground

Addressing

The module is addressed using the CS pin.

SPI Comms

The device uses SPI for comms with the MCU.

Note that the chip only has a MOSI pin (DIN) to receive commands/data. Current implementation does not multiplex this pin to allow reading from the module.

A good Arduino library to use on the Arduino side is the Waveshare Library (https://github.com/waveshare/e-Paper)

Implementation details

The custom chip supports many (but not all) of the SPI commands specified in the Waveshare datasheet. Moreover, for the simulation some of the commands make no sense to implement (there's no internal circuitry to drive for example, so the various driver commands are not needed.) The section below lists the supported command groups with links to the appropriate section in the document when useful.

reset

This command resets the chip to power on. This is slightly different than described in the document and may be changed in future to align better

write memory coordinate addresses

These commands are used to:

• set limits on the values of the x,y coordinates (useful when creating 'windowed' writes)
• set the values of the x,y pointers themselves,
• set the manner of incrementing of the pointers when writing to display memory

write to memory areas

These commands are used to write data to video memory (not the display) using values of x,y coordinates.

update display

These commands are used to control the manner in which the display should be updated (partially implemented) as well as actually executing the display.

Note Partial update is not supported well yet

ink - Section 7.3.6

Attributes

The chip defines a number of attributes that can aid in debugging operation when used in Wokwi.

Name	Description	Default value
debug	(0 or 1) when set to true, debug logs can be seen in the browser's developer tool window. This can be useful to confirm whether the operation of the program and chip is as expected	0
debugMask	8 bit mask used to contro various debug aspects: 0x01 pin changes 0x02 SPI comms 0x08 timers 0x80 general chip behaviour	0
color	(red or yellow) ePaper color when working in 3c mode	red
version	(1 or 2) ePaper 2.9" board version. Version 1 is BW, Version 2 supports color. Version 2 is better supported	2
actMode	Activation mode refers to the way the chip implements activation: 0 - the default mode, causes the display to update like a full refresh has taken place 1 - this activation mode updates the display with the minimum delay 2 - this activation mode is meant to simulate fading in/out of the display 3 - scanline mode refreshes the screen one scanline at a time Note that the display is busy while activation takes place	0

Simulator examples

• Waveshare 2.9" Custom Chip