I2C FM Receiver Circuit with LCD - 16F88 BK1080

Digital FM Receiver

This is a simple stereo FM radio receiver circuit that can scan with 87.5 MHz and 108 MHz seamlessly between 100 kHz step and it use BK1080 as a receiver IC.

Main components of this receiver are a PIC16F88 micro-controller, 16x2 LCD and BK1080 FM receiver chip. This system is design to work with 5V DC power supply. User interface of this system consist with 6 push buttons and a 16×2 character LCD module. All the functions of this receiver can control by this buttons and necessary information displayed on the LCD.

Specifications of this receiver

• Easy to build
• Standby mode
• Automatic gain control
• Automatic frequency control
• Automatic noise suppression
• Preset memory stations up to 250 (default 20)

Schematic of BK1080

BK1080

The BK1080 FM receiver employs a low-IF architecture, mixed signal image rejection and all digital demodulation technology. The stations scan of BK1080 searches radio stations based on both the channel RSSI estimation and signal quality assessment, increases the number of receivable stations while avoids false stops. BK1080 enables FM radio reception with low power, small board space and minimum number of external components. All functions controlled through an I2C serial interface. See datasheet for more details.

Numbers of memory locations are determine by the value of Eeprom 1 (default value 0x14).
You can connect an earphone directly with BK1080’s output. However, do not connect speakers directly with IC. I recommended you to use amplifier if you wish to get more sound. In addition, be carefully when soldering BK1080. Because this IC more sensitive to electrostatic. Use DC soldering Iron to solder this IC or unplug your iron when solder. Micro-controller runs using its internal oscillator. RA0 and RA1 are configuring as SCL and SDA. RA2 is not connected. RA6 pin can directly connect with background light of LCD display. As well as it is also can used for the controlling another device like mute pin of power amp.

Selecting the station:
When we are in the power on mode, on the screen we can see "Frq:107.5 Ch:12" - tuned frequency of the station and then the number of the cell where the recorded frequency of the station. Pressing ‘CH_UP’ and ‘CH_DN’ we can move the recorded stations. Pressing ‘FR_UP’ and ‘FR_DN’ we can change the frequency. ‘STORE’ stored the current frequency to the current station and ‘PWR’ used to toggle standby mode and power on mode

Firmware of this system was written by using MikroC for PIC and schematic, hex and Proteus files are available for download.

BK1080 FM Receiver

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PLL Synthesized FM Receiver Circuit with LCD - 16F88 LM7001

FM Tuner

This is high quality stereo digital PLL synthesized FM radio receiver circuit that can scan with 76 MHz and 108 MHz seamlessly between 100 kHz step, although the sensitivity is high.

Main components of this receiver are a PIC16F88 micro-controller, 16x2 LCD, LM7001 PLL Frequency Synthesizer, AN7223 IF Amp, TA7343 MPX and a FM Tuner. This system is design to work with 12V DC power supply and the LM7805 and 7808 regulators used to manage power requirements to the above-mentioned components.

User interface of this system consist with 6 push buttons and a 16×2 character LCD module. All the functions of this receiver can control by this buttons and necessary information displayed on the LCD.

Specifications of this receiver

• High sensitivity
• Standby mode
• Preset memory stations up to 250 (default 20)
• 3-user selectable frequency ranges (default 87.5-108)

Schematic of PLL and Power circuit

Schematic of micro-controller and user interrface

LM7001

The LM7001 is a PLL frequency synthesizer LSIs for tuners, making it possible to make up high performance AM/FM tuners easily. These LSIs are software compatible with the LM7000, but do not include an IF calculation circuit. The FM VCO circuit includes a high-speed programmable divider that can divide directly seven reference frequencies. Serial input circuit for data input (using the CE, CL, and DATA pins)

Tuner 

Anticipating the objection that these tuners do not find, I assure you that if you do not be lazy and go through the repair shops where repair radio. In addition, you can get this tuner from old audio system and car set. There are 3 types.

Types of tuner

1. FM Front End only (you need to build IF Amp, MPX circuit)
2. FM Front End with IF (you need to build MPX)
3. FM Front End IF and MPX

IF Amp and MPX

For IF amp I used AN7223 because it need few external parts and it has high sensitivity and stability. If you cannot find FM quad coil then you can use 2pin 10.7MHZ ceramic resonator for that (see datasheet for more details). However, it is possible to use another IC for this as AN7220, TA7640 and KA2297 etc.

For MPX decoder here I used TA7343. This IC decode mono signal to stereo. This is an optional part. If you wish to work with mono, then omit this part and connect amplifier input with ‘AF’.

IF and MPX circuit

Complete circuit

Operation

Numbers of memory locations are determine by the value of Eeprom 1 (default value 0x14) and frequency range is determine by the value of Eeprom 2 (default value 0x00).

• If value is 1 then range is 76-108MHz
• If value is 2 then range is 76-90MHz
• Else, range is 87.5-108 MHz

Selecting the station:
When we are in the power on mode, on the screen we can see "Frq:106.5 Ch:15" - tuned frequency of the station and then the number of the cell where the recorded frequency of the station. Pressing ‘CH_UP’ and ‘CH_DN’ we can move the recorded stations. Pressing ‘FR_UP’ and ‘FR_DN’ we can change the frequency. ‘STORE’ stored the current frequency to the current station and ‘PWR’ used to toggle standby mode and power on mode

Micro-controller runs using its internal oscillator. RA6 pin can directly connect with background light of LCD display. As well as it is also can used for the controlling another device like mute pin of power amp. For VCC (tuning voltage) you can use up-to 12v.

Firmware of this system was written by using MikroC for PIC and schematic, hex and Proteus files are available for download.

PLL Tuner

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Stereo Bass Booster Circuit with Simple Mixer

Bass Booster

A Bass Booster is an audio device, which amplifies the low frequencies (bass) within the audio spectrum. This operates in a similar manner to an audio equalizer. General-purpose equalizers are often not effective at boosting very low frequencies, and therefore many electronics enthusiasts make their own circuit to achieve this purpose. Using following circuit you can boost frequencies below 60Hz.

Schematic

This circuit is an active circuit and used TL074, which include separate four op-amps. Alternatively, you can use any general-purpose op amp such as LM324, TL084, etc. This circuit is not only a bass booster it also include a simple mixer circuit. U1A and U1D are act as mixer, U1B and U1C for the base boosting. I design this circuit for electronic switching. Therefor I used two transistors for it. To enable bass boost connect ‘ubb’ to positive supply. You can use normal switch for it. In addition, it is possible to enable bass boost by applying voltage signal to ‘ubb’, which come from a micro-controller or any other source. This circuit can operate in either single supply or dual power supply.

For single power supply

• Omit C20 and C21.
• Connect positive supply to VDD and Ground (0v) to GND or VAA.
• Max Supply voltage is 12v.

For dual power supply

• Remove J3 (jumper), C15, R19 and R20.
• Add jumper (0 Ohms) for R20 it.
• Connect positive supply to VDD, negative for VAA and Ground (0v) to GND.
• Max Supply voltage is +/-12v.

Please ignore the U2, R21, C16, C18 and P1. Those are not necessary for the operation of this circuit. These parts are optional because that this circuit and PCB were designed for my personal project.

Now connect output of this circuit with amplifier input and give your input to the mixer side. This circuit is ideal for high quality sound. If you want that unique clean high-bass sound then this circuit can provide it.

Schematic and PCB files were added to the download and you can download from it below.

X-Bass Sch & PCB

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10 Band I2C Graphic Equalizer Circuit - 16F628 TEA6360

Updated:

• 2016-08-17 - Added small application for calculate frequencies and parts.

10 Band Equalizer

A graphic equalizer is a high-fidelity audio control that allows the user to see graphically and control individually a number of different frequency bands in a stereophonic system. A typical graphic equalizer consists of several audio filter/amplifiers, each centered at a specific frequency in the audio range. Most graphic equalizers have two identical sets of filter/amplifiers, one for each channel in a stereophonic system.

The gain controls in most graphic equalizers are slide potentiometers that are adjusted by moving a controller up or down. Gain is increased by sliding the upwards. The slide potentiometers for each channel are placed side-by-side, with the lowest-frequency unit at the left and the highest-frequency unit at the right. In this way, the positions of the buttons appear to follow a graphical curve that represents the gain as a function of frequency for each channel.

By using following circuit you can build a 10 band stereo graphic equalizer that can be controlled via I2C system. For this circuit I used two of TEA6360 ICs. Each IC contains two serial five bands equalizer blocks. Therefore, we need two ICs for 10 bands. We can reduce the size of circuit because all the function can be drive via i2C. So that, we do not need connect potentiometers to control the gain of frequency bands like an ordinary equalizer. In addition, we can reduce cost and complexity of circuit using this IC.

Schematic

Circuit on PCB

In my demo code, I used 16F628A micro-controller and single button to set equalizer modes. The modes are ‘Flat’, ’Rock‘, ’Pop‘, ’Jazz‘ and ’Party’. The status will indicate by five LEDs those connected to PORTA. In addition, selected mode saved to device Eeprom and load to ICs when start up. However, according to your choice you can able to change the code.

For example if you need to set gain for each frequency manually, then you can add 1 button to each channel and total 10 buttons. For another example, you can add 3 buttons. One button to raise the gain and other to lower and 3rd one for select desired frequency.

The center frequency of each bands are 31Hz, 62Hz, 125Hz, 250Hz, 500Hz, 1KHz, 2KHz, 4KHz, 8KHz and 16KHz. the Q (quality) factor is 1 to 1.2 and PCB, full schematic and sample code can be downloading in below.

Part List

• C04, 07, 08, 09 = 0.37uF
• C10, 11, 12, 13 = 0.18uF
• C14, 15, 16, 17 = 0.01uF
• C18, 19, 20, 21 = 0.047uF
• C22, 23, 24, 25 = 0.022uF
• C27, 28, 30, 31 = 0.01uF
• C32, 33, 34, 35 = 0.0052uF
• C36, 37, 38, 39 = 0.0027uF
• C40, 41, 42, 43 = 0.0015uF
• C44, 45, 46, 47 = 720pF

TEA6360

The 5-band stereo equalizer is a 12C-bus controlled tone processor for application in car radio sets, TV sets and music centers. It offers the possibility of sound control as well as equalization of sound pressure behavior of different rooms or loudspeakers, especially in cars.

FEATURES

• Monolithic integrated 5-band stereo equalizer circuit
• Five filters for each channel
• Center frequency, bandwidth and maximum boost/cut defined by external components
• Choice for variable or constant Q-factor via I2C software
• Defeat mode
• All stages are DC-coupled
• I2C-bus control for all functions
• Two different module addresses programmable.

10 Band Equalizer
Calculator App

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USB Controlled 8x40 Dot Matrix Moving Display Circuit - 18F2550

2015-04-12 Initial release
2015-04-16 Wrong Configuration Bits - Fixed

This dot matrix moving display message board will be of five, 8x8 dot matrix, which will be able to display 10 different messages and maximum 60 characters of each. You can set messages by using PC application that created by me using visual basic and those messages will show on matrix display. When the circuit is disconnected form PC then default messages displayed on the display.

Circuit Diagram

PIC18F2550 is the micro-controller and main part of this circuit. This IC used because it has built-in USB transceiver that used to communicate with PC application. PORTB of IC controls the row of Matrices. This PORTB pins then connected to display through the ULN2803 IC, which consists of 8 Darlington arrays. Because micro-controller unable to handle heavy load. In the diagram, you can see 8 NOT gates. These gates used only simulation in Proteus. Therefore, you should replace with these gates with ULN2803 IC. The columns are driven by the outputs of a 40-bit serial-in-parallel-out arrangement constructed by cascading five 74HC595 ICs. The 74HC595 device is an 8-bit serial-input and parallel/serial output shift register. The serial output feature allows cascading of multiple 74HC595 devices. The time format of PC must be in English, otherwise time will not display properly on the display. LED is indicated that whether USB cable connected or not and Scrolling speed of circuit can be change by varying the value of VR1. Supply voltage for this circuit is 5v.

The PC application and other files can be download from below link.

PC App
HEX File

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