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1 | ------------------------------------------------------------------------------- |
2 | NXP PCA9571 | |
3 | ------------------------------------------------------------------------------- | |
4 | ||
5 | The NXP PCA9571 chip is an 8-bits I²C output expander. | |
6 | ||
7 | Details: | |
8 | https://www.nxp.com/products/analog/interfaces/ic-bus/ic-general-purpose-i-o/remote-8-bit-general-purpose-outputs-for-1-mhz-i2c-bus:PCA9571 | |
9 | https://www.nxp.com/docs/en/data-sheet/PCA9571.pdf | |
10 | ||
11 | ||
12 | Logic analyzer setup | |
13 | -------------------- | |
14 | ||
15 | The logic analyzer used was a Hobby Components HCTEST0006 (at 2 MHz): | |
16 | ||
17 | Probe I²C signal | |
18 | ---------------------- | |
19 | 0 SDA | |
20 | 1 SCL | |
21 | ||
22 | ||
23 | Data | |
24 | ---- | |
25 | ||
26 | The sigrok command line used was: | |
27 | ||
28 | sigrok-cli -d fx2lafw -c samplerate=2mhz --time <time> \ | |
29 | --channels 'D0=SDA,D1=SCL' -o <filename.sr> | |
30 | ||
31 | ||
32 | This is a set of example captures of NXP PCA9571 I/O accesses. | |
33 | ||
34 | Three traces are included: | |
35 | ||
36 | - pca9571_simple.sr: a simple output write operation. | |
37 | ||
38 | - pca9571_sequence.sr: 64 consecutive write operations. | |
39 | ||
40 | - pca9571_warning.sr: this produces a warning because the first read value | |
41 | is different from the expected one (the PCA9571 start-up 8-bits port | |
42 | status is high logic level 0xFF). This may occur if the first monitored | |
43 | operation is a read operation and the PCA9571 is not in its default state | |
44 | or if the PCA9571 reboots during the monitoring. |