Microcontroller projects 1

  
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In 1991, I was very interested on this display but I can`t find one in the town and expensive to import from abroad. But now, it`s everywhere and I can say that this technology is obsolete since the colorful TFT display is easy to find and cheap. The mcu is AT89S51/52, connected to a 128x64 graphic LCD and time keeper DS1302. Many manufacturers pr
Microcontroller projects 1 - schematic

oduce this LCD so be careful of differentpinout, refer toits original datasheet. DS1302 with trickle-chargeable to charge the backup battery connected to it, in this project I use a 1F/5. 5V. Yes, one Farad capacitor. After weeks charged, I test the backup function by disconnecting the power supplyfor a month, hohooo the time is still correct and continuously counting. So if you want to safe a little money, I recommend you to use smaller capacitor like 0. 47F or 0. 33F. The crystal quality for DS1302 is very substantial, the small frequency error will lead to accumulated time drift. Pull up resistors area must, you`ll face a strange circuit behaviour if not installed. Need USB solution for your project Use LPC2148 MCU. In old days it`s very handy using LPT or COM to interface your project to PC but today they are vanished just like dinosaur. All switch status can be monitored on the PC, as well as the ADC value. The LEDs are turn on/off by the first byte sent from PC. In my project input and output buffer size are 4 bytes each, you can increase the buffer depends on your need. To me, this project is about perfect because the program on PC can recover the connectionwhen temporary USB cable disconnection occurs. The VB program recognize the device from its Vendor ID (C251) and Product ID (1301). Thiscircuit work onpoll-based communication, meaning theMCU will reply when receive request fromPC. So when USB disconnected, there...



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