Changes between Version 34 and Version 35 of gpio

Timestamp:

09/12/2023 10:08:28 PM (8 months ago)

Author:

Blake Stewart

Comment:

Blink LED / GPIO DIO control, Spelling errors, updated for Venice

gpio

@@ -275 +275 @@
 Note that {{{gpioset}}} (and all libgpiod apps) will revert the state of a GPIO line back to its original value when it exits. For this reason if you want the state to persist you need to instruct {{{gpioset}}} to wait for a signal and optionally detach and run in the background.
 
-Examples:
- - Venice; use gpiofind/gpioget/gpioset on the GPIO named 'pci_wdis#'
+Examples (Venice):
+ - Use gpiofind/gpioget/gpioset on the GPIO named 'pci_wdis#'
 {{{#!bash
 # gpiofind pci_wdis#
@@ -284 +284 @@
 # gpioset --mode=signal --background gpiochip 3 7=0
 }}}
-  - Note that once gpioset exits its process the GPIO's it changed will revert back to their prior state (by design) therefor we run it above with {{{--mode=signal}}} telling it to continue to run into it receives a signal and (optinally) {{{--background}}} telling it to detach from the controlling terminal to give our shell back.
- - Newport
-{{{#!bash
-root@bionic-newport:~# apt install gpiod
-...
-root@bionic-newport:~# gpiodetect
-gpiochip0 [gpio_thunderx] (48 lines)
-gpiochip1 [pca9555] (16 lines)
-root@bionic-newport:~# gpioinfo gpio_thunderx
-gpiochip0 - 48 lines:
-        line   0:      unnamed       unused   input  active-high
-        line   1:      unnamed       unused   input  active-high
-        line   2:      unnamed       unused   input  active-high
-        line   3:      unnamed       unused   input  active-high
-        line   4:      unnamed  "interrupt"   input  active-high [used]
-        line   5:      unnamed       unused   input  active-high
-        line   6:      unnamed       unused   input  active-high
-        line   7:      unnamed       unused   input  active-high
-        line   8:      unnamed "mmc_supply_3v3" output active-high [used]
-        line   9:      unnamed       unused   input  active-high
-        line  10:      unnamed       unused  output  active-high
-        line  11:      unnamed       unused   input  active-high
-        line  12:      unnamed       unused   input  active-high
-        line  13:      unnamed       unused   input  active-high
-        line  14:      unnamed      "user2"  output  active-high [used]
-        line  15:      unnamed       unused  output  active-high
-        line  16:      unnamed       unused  output  active-high
-        line  17:      unnamed       unused  output  active-high
-        line  18:      unnamed       unused  output  active-high
-        line  19:      unnamed       unused  output  active-high
-        line  20:      unnamed       unused   input  active-high
-        line  21:      unnamed       unused   input  active-high
-        line  22:      unnamed       unused   input  active-high
-        line  23:      unnamed       unused  output  active-high
-        line  24:      unnamed       unused   input  active-high
-        line  25:      unnamed       unused   input  active-high
-        line  26:      unnamed       unused   input  active-high
-        line  27:      unnamed       unused   input  active-high
-        line  28:      unnamed       unused  output  active-high
-        line  29:      unnamed       unused   input  active-high
-        line  30:      unnamed   "pps-gpio"   input  active-high [used]
-        line  31:      unnamed      "user1"  output  active-high [used]
-        line  32:      unnamed       unused   input  active-high
-        line  33:      unnamed       unused   input  active-high
-        line  34:      unnamed       unused   input  active-high
-        line  35:      unnamed       unused   input  active-high
-        line  36:      unnamed       unused   input  active-high
-        line  37:      unnamed       unused   input  active-high
-        line  38:      unnamed       unused   input  active-high
-        line  39:      unnamed       unused   input  active-high
-        line  40:      unnamed       unused   input  active-high
-        line  41:      unnamed       unused   input  active-high
-        line  42:      unnamed       unused   input  active-high
-        line  43:      unnamed       unused   input  active-high
-        line  44:      unnamed       unused   input  active-high
-        line  45:      unnamed       unused   input  active-high
-        line  46:      unnamed       unused   input  active-high
-        line  47:      unnamed       unused   input  active-high
-root@bionic-newport:~# gpioget gpio_thunderx 24 # read gpio24 (DIO0)
-1
-root@bionic-newport:~# gpioset gpio_thunderx 24=0 # drive low gpio24 (DIO0)
-}}}
+  
+ - Finding DIO1 and setting it to output 1
+{{{#!bash
+# gpioinfo | grep dio
+        line   7:       "dio0"       unused   input  active-high 
+        line   9:       "dio1"       unused   input  active-high 
+# gpiofind "dio1"
+        gpiochip0 9
+# gpioset --mode signal gpiochip0 9=1
+}}}
+
+- Note that once gpioset exits its process the GPIO's it changed will revert back to their prior state (by design) therefore we run it above with {{{--mode=signal}}} telling it to continue to run into it receives a signal and (optinally) {{{--background}}} telling it to detach from the controlling terminal to give our shell back. Another process cannot take control of the GPIO if it is being controlled already.
 
 References:
  * https://elinux.org/images/9/9b/GPIO_for_Engineers_and_Makers.pdf
+ * https://kernel.googlesource.com/pub/scm/libs/libgpiod/libgpiod/+/v0.2.x/README.md
+
+=== Controlling DIO pins with a script or C
+Gateworks SBCs have many exposed GPIO pins through headers, but only a few of them are DIO pins which can be controlled by a userspace program and connected to outside electronics, e.g. a LED.
+
+ 
+Note: Most of the exposed GPIO pins have special purposes to communicate with peripherals. Most of the internal GPIOs (from gpioinfo) are not connected internally and can be ignored.
+
+Before connecting any outside electronics to a GPIO pin, refer to the hardware manual for your exact device to avoid any damages.  
+
+Examples (Venice): 
+- Blink a LED using a script
+{{{#!bash
+#!/bin/bash
+
+#Use gpiofind to locate chip & line of DIO0
+DIO0=$(gpiofind dio0)
+status=0
+
+while true; do
+        gpioset --mode=time --sec=1 $DIO0=$status #gpioset holds the line for 1 second
+        status=$((1-status)) #Status (LED) is inverted
+        echo $DIO0 is set to $status
+done
+}}}
+
+- Blink a LED using C (Board specific)
+{{{#!c
+#include <gpiod.h>  //Requires gpiod to compile
+#include <stdio.h>
+#include <unistd.h>
+
+int main(int argc, char **argv) {
+        const char* chip_name = "gpiochip0";
+        const int gpio_line = 7; //DIO0 on GW7201; see gpiofind command
+        struct gpiod_chip* chip = gpiod_chip_open_by_name(chip_name);
+        struct gpiod_line* line = gpiod_chip_get_line(chip, gpio_line);
+
+        gpiod_line_request_output(line, "blink", 0);
+        int status = 0;
+
+        while(true){
+                gpiod_line_set_value(line, status);
+                printf("%s %d set to %d\n", chip_name, gpio_line, status);
+                sleep(1);
+                status = 1-status;
+        }
+        return 0;
+}
+
+}}}
+
+- Both programs make the desired pin output 3.3v and 0v for a second each. 
+
+- Refer to https://kernel.googlesource.com/pub/scm/libs/libgpiod/libgpiod/+/v0.2.x/README.md for more info.
 
 [=#sysfsgpio]