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1 | ------------------------------------------------------------------------------- |
2 | ST7735 TFT display controller, 4-wire SPI | |
3 | ------------------------------------------------------------------------------- | |
4 | ||
5 | This capture contains ST7735 TFT display controller communication which is | |
6 | popular for small (1.44", 1.8") 16-bit color display modules. The protocol | |
7 | of these modules is based on SPI, but unlike typical SPI has no MISO and uses | |
8 | two additional pins called RES (reset) and DC (data / command). | |
9 | ||
10 | Details: | |
11 | https://cdn-shop.adafruit.com/datasheets/ST7735.pdf | |
12 | https://github.com/adafruit/Adafruit-ST7735-Library | |
13 | ||
14 | ||
15 | Logic analyzer setup | |
16 | -------------------- | |
17 | ||
18 | The 1.44" 128x128 px module was driven by Arduino Uno and Adafruit ST7735 | |
19 | library. The capture was taken with 8 channel noname Saleae logic analyzer | |
20 | clone, sampling 5 logic channels at a rate of 24MHz: | |
21 | ||
22 | Probe ST7735 | |
23 | ------------------ | |
24 | 0 CS (chip select) | |
25 | 1 RES (reset) | |
26 | 2 DC (data / command) | |
27 | 3 MOSI (master out, slave in) | |
28 | 4 SCLK (clock) | |
29 | ||
30 | ||
31 | Data | |
32 | ---- | |
33 | ||
34 | This is a minimal capture despite the fact that it might look otherwise. It | |
35 | contains an initialization of a display and filling it with one complete frame. | |
36 | Long pauses are caused be sleeps for a few hundreds of milliseconds, which are | |
37 | required by the spec. Other oddities like frequent changes of CS are caused by | |
38 | specific library implementation. | |
39 |