Manage constrained resources¶
This technical note discusses the options available to manage constrained resources when using an e-paper display.
SRAM¶
The frame-buffer needed for preparing and keeping the images resides in the internal SRAM of the MCU. The sizes for each panel are listed in this table.
If the internal SRAM of the MCU is too limited, an external SPI SRAM can be used.
The technical note provides the procedure to Use external SPI SRAM for frame-buffer.
Note that the external SPI SRAM is slower than the internal SRAM.
Flash¶
The fonts are stored in the internal Flash of the MCU.
If the internal Flash of the MCU is too limited, an external SPI Flash can be used.
The technical note provides the procedure to Use external SPI Flash for fonts.
GPIOs¶
Driving an e-paper display through the EXT3 extension board requires a minimum of 8 signals, and up to 16 signals with touch and external memory.
| Signal | Minimal | Touch | Optional |
|---|---|---|---|
| Power | +3.3V, Ground | ||
| SPI bus | Clock, Data in | Data out | |
| Panel | Select, Reset, Busy, Data/Command | Second select | |
| Flash | Select, Second select | ||
| I²C bus | Clock, Data | ||
| Touch | Reset, Interrupt | ||
| Total | 8 | 4 | 4 |
The technical note provides the procedure to Use GPIO expander.
Power¶
An optional external power circuit can manage the power of the panel, with a dedicated signal to turn it on and off.
The Low-power page describes the corresponding functions.
Temperature¶
The screens with embedded fast update and the screens with wide temperature operate at different temperature ranges for fast and global update.
The technical note provides the procedure to Manage temperature.