Turn-key PCB assembly services in prototype quantities or low-volume to mid-volume production runs

Thermistor based thermometer

This thermometer doesn’t use any fancy digital temperature sensors – it is based on NTC thermistor which resistance depends on ambient temperature. Design is based on Atmel89S52 microcontroller which drives four 7 segment LED displays and reads temperature value via external 12-bit ADC (LTC1298). ADC values are read through SPI interface. Reading accuracy is about 0.1ºC accuracy. Continue reading

Interfacing IDE hard drive with 82C55 microcontroller

Have you ever thought about of having huge amount of backup memory in your embedded system. The only cheap way is to connect IDE hard drive. And it seems that interfacing IDE isn’t that hard as it may seem.   The software provided for download doesn’t support any of file system formats like FAT16, FAT32 or any other. It just provides ability to access raw sectors. With 82C55 microcontroller running at 14.7456MHz reading speed reached 24 kbytes/s. Continue reading

Simple and cheap AT89S learning board

If you decide to learn microcontrollers you always need a real board to test programs in reality. Using development boards rather than simulators is more exciting as you can see really working results…or not:). Tahan Prahara have developed simple cheap AT89Sxx development board that every beginner can build for learning assembly or C language programming.     Board can be equipped with one of 40pin MSC-51 series microcontrollers: 89S51, 89S52 or 89S53. S letter means that these microcontrollers are ISP programmable. Board schematic is simple as it has plain 32 GPIO pins available including serial port communication TxD and RxD pins. It is powered via simple 5V voltage regulator circuit. ISP programming adapter probably is the lowest budget. Personally me – I wouldn’t recommend to use it without additional protection circuitry like 74HC244 buffering. But anyway this also works ok if there is no power problems. PCB is single side and easy to build by using any methods you use at home including Laser printer toner transfer or ultraviolet exposing. Continue reading