85 lines
2.8 KiB
Plaintext
85 lines
2.8 KiB
Plaintext
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1. Introduction
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This is a driver for ED060SC4 800x600 e-ink display panel manufactured by
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Prime View. Note that this driver uses a direct connection to the panel from
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the processor; it does not use a separate controller chip between the processor
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and the panel.
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To use the driver, you need to be able to control the following signals from
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your processor:
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Gate driver: SPV, CKV, GMODE.
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Source driver: CL, LE, OE, SPH, D0-D7.
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Power supply: +-15V, +22V, -20V, digital Vdd
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The file "example_schematics.png" shows how to connect the signals to e.g. a
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STM32L151 microcontroller. It also includes an example circuit for providing
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the panel supply voltages.
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Note that the larger panels (such as the 800x600) consist of multiple segments
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with separate gate driver signals. These can be daisy chained as shown in the
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example schematic.
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2. Frame buffer emulation
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Because there is not enough memory to store a full frame buffer on the
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processor, this driver emulates a frame buffer by storing the display data in
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blocks. It will buffer up to EINK_NUMBUFFERS blocks and then write them to the
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screen. The following #defines control the buffering. Larger numbers will
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result in faster drawing, but also use more RAM on the processor:
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#define EINK_BLOCKWIDTH 20 // Width of a single block in buffer
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#define EINK_BLOCKHEIGHT 20 // Height of a single block in buffers
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#define EINK_NUMBUFFERS 40 // Number of blocks to buffer
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After drawing your images, you should flush the buffers using the following
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command:
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gdispFlush();
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The buffers are also flushed whenever you turn the display off using:
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gdispSetPowerMode(gPowerOff);
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3. Display clearing and writing waveforms
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This driver does not know the official Prime View waveforms for driving the
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display, mostly because those are trade secrets and not publicly available.
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Instead, it uses reverse engineered waveforms that are mostly functional.
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The following #defines control the waveforms:
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#define EINK_BLINKCLEAR GFXON // Clear to opposite color first
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#define EINK_CLEARCOUNT 10 // Number of sweeps to clear the display
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#define EINK_WRITECOUNT 4 // Number of sweeps when writing to display
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Increasing the clearcount and writecount can improve contrast, but will also
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slow down the drawing and use more power.
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4. Clock speeds
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Because the driver bit bangs the display, the clock frequency of the processor
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is quite significant. This is controlled by EINK_CLOCKDELAY variable. Set it
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so that the delay is atleast 50 nanoseconds.
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5. Support for other kinds of panels
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Most of the Prime View panels should work using this driver, but only ED060SC4
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has been tested so far. Some points of consideration:
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- Some displays may use 4 bits per pixel. The driver currently assumes 2 bits
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per pixel.
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- Larger displays may require some other way of daisy chaining than shown in
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the example schematics.
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