SDownldr.exe is a software to program a AT89S51/AT89S52 serially through the parallel port. This Software is included in the Microcontroller Project
Circuit diagram for this ISP downloader is as follow:
The Serial Downloader circuit above using the power supply from the parallel port. However, not all parallel port capable of providing enough current for this purpose. If Your parallel port is not strong enough for this purpose, then you must provide a + 5V power supply for this circuit.
If the program is run from the IDE, then all the settings will be performed by the IDE. Whereas if it is executed as a standalone program, then the settings are as follows:
- Default Hex File If you are using the “Microcontroller Poject” IDE, so whenever performed a successful compilation, a hex file is created in the temp directory, i.e. TMPFILE.HEX. If the “Default Hex File” is checked, then the file will be sent if the Send button is clicked is the hex file of successful compilation result. Keep in mind that the hex file will exist only if the IDE is still running. If “Default Hex Files” is not checked, then you can determine which files will be sent by clicking on the Browse button.
- Send Use this button to start sending the specified hex file.
- Read Use this button to read the code on the chip. The reading will only succeed if the chip has not been locked.
- Lock Use this button to lock the chip so that the code on the chip cannot be read again.
- Port Select the appropriate port address for the port being used. Parallel port usually placed on the address 378H.
- Auto Lock If checked, then after sending the data is complete and after verification, the chip will be locked automatically.
- Browse Use this button to choose a hex file will be sent. This button will only be active if the “Default Hex Files” is not a check.
- Read data count Used to determine the amount of data to be read if the Read button is clicked. It could use a decimal number or hexadesimal, i.e. if the “Hex” is checked.