Atmel Write

chip atmel
In-System Programming(ISP) for 8051 Atmel microcontrollers

at89s8252, at89s8253, at89s51, at89s52, at89s53, Atmega8, Atmga8515, Atmega8535

Versão em português, clique aqui !

Works thru serial port, also with USB to Serial cable converters. Very simple and cheap circuit, runs in all Windows versions, from 9x to Windows 7.

Click here for the old parallel port version

Also works with USB-serial converter cables with Prolific chip, but it's slower than "onboard" serial port.
If you successfully test with another converter cable model, please mail me.

Cable model FT232BM = OK. Slow speed, about 1 byte per second (by Douglas Daniel)
Cable model GMUS-03 = OK. Uses Prolific PL2303 chip, faster than FT232BM (by Eduardo Soppa)
Adapter QUATECH PCMCIA SSP 100  = OK. (by Walter Moreira)

Check the "help button" inside the software for information about the reset switch (SW1).


Previous Version (v.3.1): "Fast" write mode, only first bytes are checked. (suggested by Cristian
Download: 11/12/2011 - V.3.1  (426K) (english)

Latest version (v.3.2):
Download: 05/11/2016 - V.3.2  (431K) (portuguese)
Atmel Write image



Schematics using PC Computer serial port control pins instead of traditional RX and TX pins. This way, software creates a SPI communication by pulsing these pins then program microcontroller's memory.


MAX232 = HIN202, ADM202
Power the circuit with 5V. Use 100uF capacitor between 5V and ground.
Check the datasheet for corresponding pins for Atmega.
Pins for DB9 female are from solder side. Do not forget to connect pin 5 to ground.
Leave crystal connected.

The circuit is powered by regulated 5V and MAX232 can also be connected thru good quality USB-Serial adapter cable.
usb-serial cable

FTDI Adapter

An simplification is by using an FTDI adapter, usually sold as Arduino programmer and known as FT232. No MAX232 needed, just check if your converter has DTR, CTS and RTS pins on sides and connect them directly. The Atmel 5V power supply can come from converter. Leave crystal and reset switch connected as in previous circuit.

adaptador FTDI

Old version for parallel port. Only for AT89S series

Compatible with old Blast8252 ISP software. Runs on Windows versions 9x, ME, 2000 and XP.

Works in Linux with Wine. Must be run as root user. Check the configuration file and add this on [ports] section:

"read" = "0x378,0x379,0x37a,0x77a"
"write" = "0x378,0x379,0x37a,0x77a"

Download: Feb 17, 2008 - V.2.11  (468K)  (Portuguese language only, parallel port version)  

Original Hardware: 

old chematic

Use 74HCT126 only. (LS series will not work). Power the circuit with 5V.


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