Advantech ITA-5831 Series, Руководство пользователя

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ITA-5831 User Manual 68
6.3 Example
Here is an example based on ITA-5831, assuming that GPIO 00 is set as output and
GPIO 7 is set as input, with the two pins interconnected. GPIO 00 corresponds to
PCA9554 0x40 IO0, while GPIO 07 corresponds to PCA9554 0x40 IO7.
To set the corresponding register, follow the instructions provided below.
Set GPIO 00 as Output
1. Read SMBUS slave 0x40 Register 3 byte value.
2. Set bit 0 of the value read in step 1 as 0 and write it to SMBUS slave 0x40 Reg-
ister 3.
3. Read SMBUS slave 0x40 Register 1 byte value.
4. Set bit 0 of the value read in Step 3 as 0 or 1 according to low or high of the out-
put value, then write it back to SMBUS slave 0x40 Register 1.
Set GPIO 07 as Input
1. Read SMBUS slave 0x40 Register 3 byte value.
2. Set bit 7 of the value read in Step 1 as 1 and write it to SMBUS slave 0x40 Reg-
ister 3.
3. Read SMBUS slave 0x40 Register 0 byte value.
4. Decide the low or high of the input value through bit 7 value read in Step 3.