#Arduino antenna tuner serial#
#Arduino antenna tuner pro#
#Arduino antenna tuner plus#

The two signals are then combined to a MONO signal. The audio output channels are to be connected as follows: the resistor R4 is to be connected to LOUT and R5 to ROUT. On the left-hand side, the I2C signal connections to the Arduino are indicated. We will work with the lowest gain of 20, which is more than high enough if you use a 8 Ohm speaker. The gain is internally set to 20 to keep external part count low, but the addition of an external resistor and capacitor between pins 1 and 8 will increase the gain to any value from 20 to 200.

It is a power amplifier designed for use in low voltage consumer applications ( datasheet ). The LM386 has been around since the seventies. I used the LM386 chip to build a mono amplifier. Pressing a button connects the input to Ground. The IO-pins D5-D12 are connected to the two keypads. The I2C-shifter further needs 5 Volts on the high-voltage side. (I bought mine on because it was two-coloured: yellow (top rows) and blue and there was no RST pin).Ĭonnect all components to the 3.3 Volt output of the Nano and to Ground. For the OLED display, it is sufficient to connect to SDA and SCL. On the 3.3 Volt side of the I2C-shifter, we connect to SDIO, SCLK and RST of the Si4703. (You can use a 9 Volt block battery instead but it might only last a few hours).Īrduino SDA (A4) and SCL (A5) are connected to the 5 Volt side of the I2C-shifter. That way, the power management of the Nano will automatically switch off the batteries when you connect the USB cable.

#Arduino antenna tuner plus#

During the first testing phase, run the circuit from the USB power supply without batteries! If you want to play it safe, use six AA batteries (9 Volt) and connect the plus pole to the VIN pin (instead of the 5 Volt pin) of the Nano. WARNING! Always disconnect the batteries before you connect the Nano via USB to your computer! Otherwise the 5 Volt from your computer will be short-circuited with your batteries. This way, a Nano will happily run from 3 AA-batteries. The batteries are connected directly to the 5 Volt pin of the Arduino Nano, bypassing the voltage regulator. (If there is no dot, wires just cross).Īs you can see, the project is powered by three AA-batteries (4.5 Volt). Next, let's look at the wiring around the Nano and the details of the I2C bus connections. Schematics Arduino connections to radio and display Both have USB connectors and are easy to use with the Arduino IDE. If you want, you can use the Uno instead. The Nano is almost identical to the Uno but on a much smaller footprint. (I linked in the description above to a I2C-shifter with 4 signals which can help you to save some cabling). We need to level-shift a total of three signals: SDA, SCL and RST. I had some I2C-shifters lying around with two signals each that I used in the project. As I really wanted to keep the display, I decided to use an Arduino Nano (16 MHz) which has 5 Volt signal level on the I2C bus and use bidirectional I2C Logic Level Converters (I2C-shifters) to connect to the 3.3 Volt bus signals of the display and radio chip. My testing showed that this is too slow to drive the OLED display.

#Arduino antenna tuner pro#

But there is another problem: the Arduino Pro Mini runs at 8 MHz, half the speed of an Arduino Uno or Nano. This means using an Arduino Pro Mini which is a little more difficult to program as it lacks a USB connector and has to programmed with an FTDI breakout. For that reason, Sparkfun advise in their hookup guide to use a 3.3 Volt Arduino. Voltages used of the Si4703 and the OLED display on the I2C bus are 3.3 Volt. On our I2C bus, the Arduino acts as master while both the Si4703 and the OLED display act as slaves. If you want to learn more about the I2C bus, Tom Igoe and Jeff Feddersen have made a great video. In the Si4703, SDA is called SDIO and SCL is called SCLK. In addition comes the Reset line (RST).More accurately, the bus is called I2C (Inter-integrated circuit pronounced I-squared-C or I-two-C) and uses only two bidirectional lines:

#Arduino antenna tuner serial#

The Si4703 has a two-wire interface, which is a serial bus that allows controlling the tuner from an Arduino over serial communication. (If you don't want to build your own amplifier, you can buy the Evaluation board instead, which you can use directly with your headphones). LOUT and ROUT are the left and right output channels that we will connect to our amplifier.