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--- hardware:raspberry_pi [2021/03/31 02:50]
nanodano [Create a system service user account]
+++ hardware:raspberry_pi [2021/03/31 17:40] (current)
nanodano
@@ Line 86: / Line 86: @@
 </code>
-===== Configure static IP address for eth0 =====
+===== Networking =====
+==== Configure static IP address for eth0 ====
 It should use DHCP by default, but if you want to specify an IP Address you can.
@@ Line 99: / Line 101: @@
 </code>
-===== Manually configure wpa_supplicant for WiFi =====
+==== Manually configure wpa_supplicant for WiFi ====
 <code bash>
@@ Line 124: / Line 126: @@
 </code>
-===== Expose local port via remote server =====
+==== Expose local port via remote server ====
 You can take a service running locally, and use a remote VPS to be a proxy and allow connectivity from the internet.
@@ Line 312: / Line 314: @@
-==== I2C stuff ====
+===== I2C stuff =====
+Turn on i2c using ''raspi-config'' under Interface options. Reboot after enabling. This will create a device like ''/dev/i2c-1''.
+Install ''i2c-utils'' to get tools like ''/usr/sbin/i2cdetect''.
+<code bash>
+sudo apt install i2c-tools
+dpkg -L i2c-tools
+sudo i2cdetect 1  # they're in sbin, so need sudo
+sudo i2cdump --help
+</code>
+==== I2C C library ====
+<code c test_i2c.cpp>
+/* test_i2c.cpp
+ * Compile with:
+ *   g++ test_i2c.cpp -lwiringPi
+ */
+#include <iostream>
+#include <errno.h>
+#include <wiringPiI2C.h>
+int main() {
+   /* Provide the i2c address from `sudo i2cdetect` */
+   int file_handle = wiringPiI2CSetup(0x60);
+   int result = wiringPiI2CWrite(file_handle, 0x40, 0xDEAD );
+   if (result == -1) {
+      std::cout << "Error #" << errno << std::endl;
+   } else {
+       std::cout << "Result: " << result << std::endl;
+   }
+   return 0;
+}
+</code>
+==== I2C Python Library ====
+Install the [[https://packages.debian.org/buster/python3-smbus|Python3 smbus]] library using ''apt''.
+<code bash>
+sudo apt-get install python3-smbus
+</code>
+<code python test_i2c.py>
+# Reference adapted from: https://pypi.org/project/smbus2/
+from smbus import SMBus
+DEVICE_ADDRESS = 80
+bus1 = SMBus(1)
+data = bus1.read_byte_data(DEVICE_ADDRESS, 0) # From offset 0
+print(data)
+bus1.close()
+with SMBus(1) as bus1:
+    # Write a byte to device address, offset 0
+    data = 45
+    bus1.write_byte_data(DEVICE_ADDRESS, 0, data)
+</code>
-i2cdetect

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