Serial Port Programmers

These programmers use the serial port on a PC to program an AVR. Most are nearly identical, but any difference is to satisfy a software requirement of the designer. All of them work equally well if you are using something like avrdude, but they are considerably slower than a parallel port programmer.

DASA

The DASA is an RS-232 to TTL level shifter circuit, which is used by software to create an ISP interface. It is significantly slower than the parallel port programmers.

Schematic

DASA schematic

DASA-2

The DASA-2 is an RS-232 to TTL level shifter circuit, which is used by software to create an ISP interface. There is a transistor used to invert the reset line. If you have active reset circuitry, and if that circuitry is open collector, this programmer will draw less current from the serial port than a DASA programmer.

Schematic

DASA-2 schematic

DASA-3

The DASA-3 is an RS-232 to TTL level shifter circuit, which is used by software to create an ISP interface. There is a transistor used to invert the reset line. If you have active reset circuitry, and if that circuitry is open collector, this programmer will draw less current from the serial port than a DASA programmer. Otherwise, there is no advantage to the increased complexity.

Schematic

DASA-3 schematic

Serial Uploaders

Discrete RS232 Uploader

The Discrete RS232 Uploader is an RS-232 to TTL serial converter circuit, used to upload code from the Arduino environment, or as a serial port for an AVR.

Schematic

Discrete RS232 Uploader schematic

MAX232 Uploader

The MAX232 Uploader is an RS-232 to TTL serial converter circuit, made using a Maxim MAX232, and used to upload code from the Arduino environment, or as a serial port for an AVR. If you leave off C5 and the connection to the RESET line, it is just an RS-232 port for your AVR.

Schematic

MAX232 Uploader schematic