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[size=+1]IntroductionThe first version of the Easy-Downloader was designed in 1997 to be used as a tool for my students on building her/his own microcontrollers circuit in the class ' Designing Microprocessors System'. The circuit features low-cost and easy use. The latest version V1.1 was designed to be used with 2051 and the newest 4051 chips. There is no separated functions like other programmer e.g., blank check, erase, write. Simply type say, c:\..>ez hello , the hex file 'hello.hex' will then be programmed to the chip automatically. If the chip is not blank or the code is locked, it will erase first, then write and verify... that all.[size=+1]HardwareFigure 1 depicts a circuit diagram of the Easy-Downloader. As shown, the circuit uses a 89C2051 with writer.hex firmware, 74LS373 8-bit latch, DS275-like, 7805, LM317 and two transistors, 2N2222A and 2N2907A. The programming voltage control circuit is the same as recommended by ATMEL application note. It can be raised from 0V, 5V and 12V by appropriated signal from P3. The 8-bit latch, 74LS373 provides some signal for selecting the programming modes. A byte to be programmed or read back is sent/received through P1. Incrementing address is done by pulsing a positive pulse to XTAL pin. The circuit may be built using simple point-to-point soldering with a general purpose PCB( fish's egg like PCB) or making PCB shown above, the file is  Easy-v1.pcb Protel PCB version 2.76. The finished board should be tested without any chips; 1) +5V supply, 2) programming voltage 0V, 5V and 12V by connecting the pin that control (P3.5 and D) 2N2222A and 2N2907 to +5V and/or GND. The adapter output should be approx. 15Vdc 100mA.

[size=+1]Acrobat PCB FilesAs suggested by a friend from Romania, Puiu Chiselita, to provide PCB image in Acrobat file, so I have asked my friend, Jaroon Keawkhrua. He made within an hour, thanks again for providing us, the Acrobat PCB file.
TOP LAYER (80kB) easy-v2t.pdf
BOTTOM LAYER (36kB) easy-v2b.pdf
COMPONENT LAYER (51kB) easy-v2o.pdf

[size=+1]Software
Two files that you should get are: writer.hex 4,871 bytes, the intel hex file firmware for 89C2051 chip ( the actual code size is 2021 bytes) and, ez.exe 20,800 bytes the uploader program run on PC, send hex file to the downloader. The original writer.c program was written in 'C'. To modify, it needs Micro C-compiler from Dunfield Development System Ontario Canada with tiny memory model.

[size=+1]Functional TestUse a given programmer (or ready made Easy-Downloader) write the writer.hex into the 2051 chip. Put the programmed 2051 chip to the board. Invoke any communication software with 9600 baud, 8-data bit, no parity. Connect DB-9 to COM1, say, press enter key, the title 'Easy-Downloader V1.1 for ATMEL 89C2051/4051' would be appeared on the screen. type >s2048 ( set byte counter to 2k), then without the 2051 chip in ZIF, type >r (read 2kB), on screen would show FFFFFFFFFFF... indicating corrected wiring for P1. If you put the chip having already program inside, r command will show the hex code with the number of byte set by s command. Try e command to erase the entire program!! All done. Figure 2 shows example of using Xtalk program to test the board.

Now try with 'ez' the uploader program to help you more easy to write the hex file to the chip. Example of using ez is shown in Figure 3. Have fun...

DownloadEZ Uploader V3.0 for Window The EZ Uploader provides a simple means of sending HEX file to the writer board. To connect the board with EZ, click available COM port, COM1, say. After the EZ recognizes the chips, then click Send Hexfile, that all. Since there is no signature byte that indicates chip number and programming voltage, thus you have to choose the appropriated memory size either 2051 or 4051 manually, i.e.,  2048 or 4096 respectively.Download EZ Uploader V3.1 for Window An upgraded version of EZ3 with RAED and SAVE AS features for reading HEX code resided in the chip and save as an Intel HEX file.
[size=+1]Tips[size=+0]HEX file extensionSome Assembler or Compiler produce output hex file with .OBJ instead of .HEX. The EZ needs .HEX extension, just rename it...[size=+0]Expensive ZIF SocketWithout expensive ZIF socket, you may use an ordinary socket instead, surely many times of pulling the chips may cause the far end leg of the 2051 chip broken. My student suggests me to insert one more socket to the 2051 chip. It works very nice. Even the programmer has ZIF, but your application board does not have. Better to insert one socket to strengthen the 2051's leg.[size=+0]DC AdapterAny DC adapters, fixed or adjustable can be used, a bridge diode corrects polarity for the regulator IC eventually. Many adapters provide higher DC output than the value labeled, to ensure, check the proper programming voltage that must be in the range of 11.5 to 12.5V.[size=+0]Putting Right PositionThe latest version does not include the protection circuit if putting wrong position, i.e., GND-Vcc <--> Vcc-GND.Thus before put the chip into the programmer or your application board, back to see your thought, say I am putting the 2051 chip to the right position, then pick the chip, and place it...
89C1051There's no problem with 89C1051 chip but ensure that the hex code must less than 1024 bytes (000H to 3FFH). While verifying after erase it showed 0 to 2048 byte as the 2051 chip, it means twice reading, i.e., 000H-3FFH then 000H-3FFH, the same physical address. When programming, the control chip will write and verify only the size of program.