Issues when configure different GPIO as SPI chip select line


#1

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.


#2

Hi,

Are those GPIOs free?
Are you using sample SPI application?

Thanks
Alex


#3

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

OK

GPIO 20~22 are available.


#4

hi everybody:
who can help me…my SL8082T AT+WIOM why have no GPIO1 and GPIO4-7?
ATI3
R7.53.1.A1.201504291449.SL8082TR 1962308 042915 14:49

OK
AT+WOPEN=2
+WOPEN: 2,“AT v06.53A1”

OK
AT+WIOM=2
+WIOM: “GPIO2”,4
+WIOM: “GPIO3”,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: “GPIO19”,4
+WIOM: “GPIO20”,4
+WIOM: “GPIO21”,4
+WIOM: “GPIO22”,4

OK

before i download my openat .then i have delete it by at+wopen=4…

i do not why?


#5

Probably those missing GPIOs are being used by other applications.