Dilshan R Jayakody’s Web Log

This project focuses on a simple yet powerful FM stereo tuner module. The core component of the module is RDA5807M , a single-chip broadcast FM stereo tuner that has gained popularity among designers in recent years due to its high level of integration. This integration significantly reduces the need for external components, simplifying circuit design. The RDA5807M supports a wide FM band, covering frequencies from 50MHz to 115MHz, making it adaptable to global FM standards. Additionally, its use of a low-IF digital architecture streamlines the design process by requiring fewer external parts. The inclusion of an AGC (automatic gain control) feature ensures consistent signal reception, even in environments with fluctuating signal strengths. FM stereo receiver module with seven segment module. The chip's digital stereo decoding capabilities deliver high-quality audio output, providing a rich stereo sound experience. Moreover, the energy efficiency of the RDA5807M makes it suitable...

YALI ( Yet Another LCD Interface ) is an open-source project to provide a universal interface to drive the popular Hitachi HD44780 LCD controller. This module supports 3.3V and 5V MCUs and hardware development platforms, including Arduino, STM32, PIC, and ESP8266. YALI hardware module. The hardware module of this project consists of a 74HCT08 CMOS AND gate and a 74HC595 8-bit serial-in, parallel-out shift register. This module uses the MP1540 step-up converter to power the LCD unit connected to the system. The module has the jumper to select 3.3V or 5V DC power input.  Bottom side of the YALI hardware module. The YALI library is developed using C and is designed to be easily integrated with any C/C++ embedded toolchain. At the initial design stages, this library was successfully tested with all Arduino development boards, NodeMCU , STM32 Blue Pill , etc. The target system must have three digital output lines with 5V or 3.3V logic levels to interface with the YALI module. As m...

At the beginning of 2018, we developed the first version of the 6-channel speaker selector using PIC16F88 MCU and ULN2803 Darlington transistor array. In this new design, we redesign it with low-cost MCU and Darlington transistor arrays. This design also provides the same functionality as the 6-channel speaker selector switch we designed earlier. This new speaker selector uses STC15W201 MCU. This MCU is a low-cost 8051 MCU designed by STC micro . At the time of this writing, the STC15W201 can obtain for less than US$ 0.8. To drive the seven segments and to control the relays, this design uses the popular 74HC595 8-bit shift register ICs. PCB of the 6-channel speaker selector. To select each speaker channel, we use pair of 12V DPDT relays. These relays interface to 74HC595 through a ULN2001D 3-channel Darlington transistor array IC. This 3-channel Darlington driver IC is functionally equivalent to the famous 8-channel ULN2003 IC. This ULN2001D version is an 8-pin IC and is av...

This is an RDA5807M based FM stereo radio module. This module is designed to replace old, low-voltage, analog FM stereo radio receiver modules. Like many digital receivers, this module also got auto scanning, station memory, and digital volume control. This module can driver using 5V to 9V DC power source. FM stereo receiver module with seven-segment display unit. The frequency range of the receiver is 88MHz to 108MHz. The auto scanner of this module can tune the receiver with 25kHz increments in up and down directions. The memory manager available with the current firmware can hold up to 10 stations in MCU EEPROM. Bottom side of the receiver module The dimensions of this module are 72.85mm × 32.0mm. With the seven-segment display, the depth of the assembled module is 37.5mm. AF output power of this module is not sufficient to handle the pair of speakers. To drive speakers, this module needs to pair with a stereo AF power amplifier kit/module .  This is an open-source hardware pro...

This project is about a simple LED clock module based on STM8S103F3 MCU and DS3231 RTC. This clock module is designed to handle a generally available 14.2mm (0.56 inch) 4-digit seven-segment displays. This module use 12-pin (6-pin × 2) socket to connect the seven-segment display to the PCB, and it allows to mount the display unit off from the PCB. Prototype version of the clock module The " alarm terminal " of this module is available as an open-collector output. This terminal allows the user to connect an external circuitry to this module. The module can power up using 5V or 3V DC power source. The necessary power source can select using a jumper in the module. This module also provides a slot to install a small CR1220 type battery to backup the time and alarm configuration. Front side of the module (without seven segment display unit) Bottom side of the module   The dimensions of this module are 65.4mm × 29.6mm. With the seven-segment display, the depth of the assembled ...

UV exposure unit is a vital component in printing and mass-manufacturing industries. I decided to build a UV exposure unit to assist my screen-printing and PCB prototyping needs. After examining the market, I decided to construct this unit using black fluorescent tubes. Those black fluorescent tubes are usually available to purchase in many electrical shops here in Sri Lanka . Finished UV exposure unit with four fluorescent tubes. To drive the exposure unit, I build an electronic controller using ATtiny2313A MCU. This controller is capable to handle the exposure unit for up to 999 seconds ( approximately 16 minutes ). This electronic controller got two high-power relay driver stages, an audible notification unit, a safety lock, and a programmable timer. The fluorescent tubes are drive using four separate chokes and starter units. For this unit, I use four NEC 20W - 60cm (T10) black fluorescent tubes.  12V, 5A SMPS is used to drive the relays and electronic controller unit. PSU, c...

This is an AT89S2051 base 8bit bus monitoring utility. This module indicates bus values using hexadecimal numbering format and notify value changes by the beep. This utility is design to work with any 5V compatible TTL/CMOS - data/address buses. This 8bit bus monitor requires 5V external power supply. In the idle mode this unit draws 15mA of current and in working mode (when inputs get change) this may raise up to 20mA – 30mA. Due to this low power profile, this system can also attach into the PSU of the "testing system". This module is release as an open hardware project and it is covered with Creative Commons Attribution-ShareAlike 3.0 license . All the project related resources are available at Open Hardware Hub .