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Analog input with ADS1115 in Python

Python has the pretty good library “WiringPi-Python“, but it depends on WiringPi2 for Raspberry Pi and cannot be installed automatically through pip. Here is a solution.

In my project I want to control a battery voltage and a charging state for my LiPo battery. Therefore I’ve added the ADS1115 board.

I’ve installed WiringPi2 for BPi and tried to read analog inputs through the gpio command line utility.

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$ gpio -x ads1115:200:0x48 aread 200

The main disadvantage of this method for me is the default analog reading settings: 128 samples per second and +/-4.096V range (my battery voltage is 4.2V). You cannot change these setting in the command line utility.

Sending SMS via MQTT. Strange? No, this is simple.

In my home automation system I need to send alarms and events via SMS to my mobile number because an internet connection is not stable and may absent on power loss. Therefore I’ve purchased a compact board with the SIM900 chipset.

sim900a

Note: SIM900A – this is an Asian version of this chip and does work in Europe. I’ve flashed the “1137B02SIM900M64” firmware and now it works well with my SIM cards. Here is the blog with many firmwares, flashing tools and instructions.

I’m using Pimatic and it does not have a ready-to-use plugin for this GSM modem. I’ve found a python code on the web that easily allows to send SMS using both ASCII and Unicode modes. My work is to create a daemon that will route MQTT messages to a SMS messages and vice versa. Pimatic has the very powerful MQTT plugin and I can send SMS messages using built-in rules.

Additionally I can process incoming SMS messages and execute commands from SMS messages by subscribing to a selected topic.

My github repository.

1-wire on Banana Pi BPI-M2 Ultra

Banana Pi BPI-M2U has the Allwinner R40 chip. This chip does not include a hardware 1-wire interface. But we can implement this data exchange protocol at the software level using the bit bang method. The default Linux kernel (Raspbian Jiessie, 3.10.107) does not include the w1-gpio kernel module. I’ve tried to compile it, but it has many dependencies. I’ve foundĀ w1-gpio-cl. This is a Linux kernel-mode driver substitutes w1-gpio 1-wire bus master driver. Contrary to the standard driver, w1-gpio-cl doesn’t need many other kernel modules. Also you may configure this kernel module using command line parameters.

Cross-compilation for Banana Pi M2U

Using BPi for kernel (re)compilation is quite painful because it is very slow for this task. So I configured a virtual machine (VMWare in my case). Now, the kernel can be compiled in 50-80 seconds on my i7-4770. The configuration is easy if you read the following tutorial. I’ve tried several options before and selected this one.

Banana Pi M2 Ultra. My start.

Some time ago I’ve purchased RPi2 and built my first smart home server (powered by Pimatic). Everything is good with this solution but currently I need more:

  1. More memory.
  2. More CPU performance.
  3. Fast internal storage (eMMC preferable).
  4. Backup battery.
  5. All wireless interfaces (Wi-fi, Bluetooth).
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