Hey guys! I’m configuring GPIO 20 as our chip select line for the SPI device. After setup, I could read the SPI_CLK and SPI_MOSI correctly. However, the chip select was always low. It should be high when no data is sent and go low when data on line.
What made the thing strange is that, when i used GPIO 1,2,3 as the chip select, everything is correct! I’m using SL808X, I’m wondering if GPIO 20,21,22 have limitations or need more configuration.
I’m not using the sample SPI code. I’m sure that those GPIOs are available.
After I erased the app on the module, I ran “at+wiom=2” to see the available gpio list.
at+wiom=2
+WIOM: “GPIO1”,4
+WIOM: “GPIO2”,4
+WIOM: “GPIO3”,4
+WIOM: “GPIO4”,4
+WIOM: “GPIO5”,4
+WIOM: “GPIO6”,4
+WIOM: “GPIO7”,4
+WIOM: “GPIO8”,4
+WIOM: “GPIO9”,4
+WIOM: “GPIO10”,4
+WIOM: “GPIO11”,4
+WIOM: “GPIO12”,4
+WIOM: “GPIO13”,4
+WIOM: “GPIO14”,4
+WIOM: “GPIO15”,4
+WIOM: “GPIO16”,4
+WIOM: “GPIO20”,4
+WIOM: “GPIO21”,4
+WIOM: “GPIO22”,4