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MicroPython Driver for TEA5767 FM Radio Module

TEA5767 is a cheap but functional FM radio module, which allow you to build DIY FM radios. It comes with an antenna via a 3.5mm jack but have no internal volume control.

This driver has been tested on ESP8266, ESP32 and RPi Pico running MicroPython v1.16. The CircuitPython version can be found here.

Wiring

Both 3.3V and 5V power works; 5V may results better sound quality.

Import and Initialize

Upload TEA5767.py to your board. You can use Thonny to do so.

To import and initialize the driver:

from machine import Pin, SoftI2C
from TEA5767 import Radio

i2c = SoftI2C(scl=Pin(5), sda=Pin(4), freq=400000)
radio = Radio(i2c)  # initialize and set to the lowest frequency
radio = Radio(i2c, freq=106.7)  # initialize and set to a specific frequency

print('Frequency: FM {}\nReady: {}\nStereo: {}\nADC level: {}'.format(
        radio.frequency, radio.is_ready,  radio.is_stereo, radio.signal_adc_level
        ))

You can also use I2C module on pins that supported hardware I2C bus (ESP8266s dno't have them):

from machine import Pin, I2C
from TEA5767 import Radio

# Hardware I2C bus 0 on ESP32
i2c = I2C(0, scl=Pin(18), sda=Pin(19), freq=400000)
radio = Radio(i2c)

Parameters

The radio can be initialized with the following parameters:

radio = Radio(i2c, addr=0x60, freq=106.7, band="US", stereo=True,
                      soft_mute=True, noise_cancel=True, high_cut=True)

Set Frequency

Set the radio to a specific frequency:

radio.set_frequency(106.7)  # set to FM 106.7

Change Frequency

radio.change_freqency(0.1)  # increase 0.1 MHz
radio.change_freqency(-0.1)  # decrease 0.1 MHz

These methods also will change the direction of search mode (see below).

Mute/standby Mode

radio.mute(True)
radio.standby(True)

radio.mute() is simply turning off the sound output. If you want to save power, use radio.standby() instead.

The TEA5767 also allows you to turn off right and/or left speaker, but I decided not to implement these functions.

Search Mode

radio.search(True)  # turn on search mode
radio.search(False)  # turn off search mode
radio.search(not radio.search_mode)  # toogle search mode
radio.search(True, dir=1, adc=7)  # turn on search mode and set search parameters

• dir = search direction; 1 = search station by increasing frequency (default), 0 = decreasing.
• adc = desired signal ADC resolution (sound quality). Available values are 0, 5, 7 (default) or 10. The radio would try to find a station which ADC level satisfied this setting.

When the search mode is enabled, the radio would attempt to find a station with strong signal whenever you set a new frequency or change it.

The radio may need a bit of time to tune on a stable signal, so it would be recommended to run radio.read() and keep updating your external display with radio.frequency on loop.

Read Status From the Radio

Some variables will be updated after calling radio.read():

radio.read()
frequency = radio.frequency
search_mode = radio.search_mode
is_ready = radio.is_ready
is_stereo = radio.is_stereo
signal_adc_level = radio.signal_adc_level

• radio.frequency: current frequency, float number (may be changed in search mode)
• radio.search_mode: search mode status (True/False)
• radio.is_ready: station is ready (signal is strong enough)? (True/False)
• radio.is_stereo: stereo mode status? (True/False)
• radio.signal_adc_level: station ADC resolution? (0, 5, 7 or 10)

You may need to call it a few times with some time delay when the search mode is enabled (the radio frequency would jump around a bit).

Manually Update the Radio

radio.update()

This method will be automatically called by many other methods of the radio. If you wish to change some parameters, you can manually call radio.update() to update radio status:

radio.stereo_mode = True
radio.stereo_noise_cancelling_mode = True
radio.high_cut_mode = True
radio.update()

By default radio.update() will wait 1 ms at the end and then call radio.read() for the I2C bus have maximum delay of 400 us.

A Simplified MicroPython Version Without Using This Driver

If you just want to set the frequency of TEA5767, you can use code as short as below (simply paste it into your script):

from machine import Pin, SoftI2C

i2c = SoftI2C(scl=Pin(5), sda=Pin(4), freq=400000)

def radio_frequency(freq):
    freqB = 4 * (freq * 1000000 + 225000) / 32768
    i2c.writeto(0x60, bytearray([int(freqB) >> 8, int(freqB) & 0XFF, 0X90, 0X1E, 0X00]))
    
radio_frequency(106.7)

This code does not read anything back and don't enable the search mode, but will turn on stereo mode, soft mute, stereo noise cancelling and high cut.