Radio Basestation

About

This project turns a typical handset (Baofeng UV-5R or similar) into a base station that receives DTMF commands and responses with information sent over the radio via text-to-speech.

Prerequistes for Ubuntu

sudo apt update
sudo apt install espeak ffmpeg libespeak1 portaudio19-dev

Hardware

• UV-5R (any handset with Kenwood microphone jack should work)
• APRS Cable
• BME280
• SDS011

Radio Setup

This program relies on the VOX (amplitude based automatic transmission) function of a handset to function properly.

You can enable VOX On the UV-5R using the following steps.

• MENU -> 4 to select VOX
• MENU again to modify values
• Use arrow keys to set VOX to 3
• MENU again save the setting

Start Program Manually

The DTMF module is primarily designed to be run as a systemd service on an embedded system. However, it can be run as a standalone python project for testing and debug purposes.

From the project root directory run:

$ pip install .

And start the program

$ python -m radiodtmf

DTMF Commands

Default / Recommended DTMF Commands

Command	Result
38 (DT)	Get the current date and day of the week
86 (TM)	Get the current time in 12 hour format
27 (AQ)	Get estimate of Air Quality Index (AQI) using EPA format
99 (WX)	Get the current weather (temperature, barometric pressure, relative humidity)
#	List commands

System Configuration

ALSA

This project uses ALSA for audio input and output. Most systems have multiple audio devices, and as such we need to identify an appropriate device and configure ALSA to use this device by default.

List ALSA devices and identify a device capable of audio input and output.

aplay -l

Identify the card number of the audio device you plan to use. Create a file in /etc/asound.conf that sets this card to the default for ALSA pcm and ctl.

# /etc/asound.conf

defaults.pcm.!card 1
defaults.ctl.!card 1

BME280

This project uses the ubiquitous BME280 multisensor chip in order to get hyper local weather information. The following guide assumes you're attaching the BME280 to a Raspberry Pi but should be adaptable to other SoCs.

4 Pin BME280 Hook Up

Most 4 pin BME280 breakout boards are I2C only and as such are hooked up to the RPi like any other device.

Board Pin	Name	RPi Pin	RPi Description
+3.3V Power	VCC	P01-1	3V3
Ground	GND	P01-6	GND
Clock (SCL/I2C)	SCL	P01-5	GPIO 3 (SCL)
Data (SDA/I2C)	SDA	P01-3	GPIO 2 (SDA)

6 Pin BME280 Hook Up (I2C)

Most 6 pin BME280 breakout boards allow the use of either the I2C or SPI but do not include a built-in logic level shifter. For this project we require the board to use I2C and will hard configure the board to use this protocol.

Board Pin	Name	RPi Pin	RPi Description
+3.3V Power	VCC	P01-1	3V3
Ground	GND	P01-6	GND
Clock (SCL/I2C) or (SCK/SPI)	SCL	P01-5	GPIO 3 (SCL)
Data (SDA/I2C) or (SDI/SPI)	SDA	P01-3	GPIO 2 (SDA)
Chip Select (High=I2C, Low=SPI)	CSB	(Connect to Board Ground)	Not Connected
Data (SDO/SPI)	SDO	Not Connected	Not Connected

IC2 Configuration

Ensure that the I2C kernel driver is enabled:

$ dmesg | grep i2c
[    4.925554] bcm2708_i2c 20804000.i2c: BSC1 Controller at 0x20804000 (irq 79) (baudrate 100000)
[    4.929325] i2c /dev entries driver

or:

$ lsmod | grep i2c
i2c_dev                 5769  0
i2c_bcm2708             4943  0
regmap_i2c              1661  3 snd_soc_pcm512x,snd_soc_wm8804,snd_soc_core

If you have no kernel modules listed and nothing is showing using dmesg then this implies the kernel I2C driver is not loaded. Enable the I2C as follows:

1. Run sudo raspi-config
2. Use the down arrow to select 9 Advanced Options
3. Arrow down to A7 I2C
4. Select yes when it asks you to enable I2C
5. Also select yes when it asks about automatically loading the kernel module
6. Use the right arrow to select the <Finish> button
7. Select yes when it asks to reboot

After rebooting re-check that the dmesg | grep i2c command shows whether I2C driver is loaded before proceeding.

Optionally, to improve permformance, increase the I2C baudrate from the default of 100KHz to 400KHz by altering /boot/config.txt to include:

dtparam=i2c_arm=on,i2c_baudrate=400000

Then reboot.

Then add your user to the i2c group:

$ sudo adduser pi i2c

Install some packages:

$ sudo apt-get install i2c-tools

Next check that the device is communicating properly (if using a rev.1 board, use 0 for the bus not 1):

$ i2cdetect -y 1
       0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
  00:          -- -- -- -- -- -- -- -- -- -- -- -- --
  10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
  20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
  30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
  40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
  50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
  60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
  70: -- -- -- -- -- -- 76 --

Local Installation

Copy system/provisioning/install.sh to the device that will be connected to the radio and run it. Note this install, enable, and start a systemd service immediately. Ensure that all system configuration is handled before running this script.

Environment Variables

Note these variables are usually set with an /etc/default file by the install script but they can be set manually for testing or alternate methods of installation.

Variable	Service	Description	Default
ALSA_DEVICE	Audio	ALSA Device for audio input and output.	0
BME280_IC2_PORT	BME280	BME280 IC2 Port.	1
BME280_IC2_ADDRESS	BME280	BME280 IC2 Address.	0x76
SDS011_DEV	SDS011	SDS011 dev file	/dev/ttyUSB0