Hardware Description
AVR STK500 User Guide 3-9
1925C–AVR–3/03
3.7.1 ISP Programming In-System Programming uses the AVR internal SPI (Serial Peripheral Interface) to
download code into the Flash and EEPROM memory of the AVR. ISP programming
requires only V
CC
, GND, RESET and three signal lines for programming. All AVR
devices except AT90C8534, ATtiny11 and ATtiny28 can be ISP programmed. The AVR
can be programmed at the normal operating voltage, normally 2.7 - 6.0V. No high-volt-
age signals are required. The ISP programmer can program both the internal Flash and
EEPROM. It also programs fuse bits for selecting clock options, start-up time and inter-
nal Brown-out Detector (BOD) for most devices.
High-voltage programming can also program devices that are not supported by ISP pro-
gramming. Some devices require High-voltage Programming for programming certain
fuse bits. See the High-voltage Programming section on page 3-11 for instructions on
how to use High-voltage Programming.
Because the programming interface is placed on different pins from part to part, three
programming headers are used to route the programming signals to the correct pins. A
6-wire cable is supplied for connecting the ISP signals to the target ISP header. A color
coding system and a number system are used to explain which target ISP header is
used for each socket.
During ISP programming, the 6-wire cable must always be connected to the header
marked “ISP6PIN”. When programming parts in the blue sockets, connect the other end
of the cable to the blue SPROG1 target ISP header. When programming parts in the
green socket, use the green SPROG2 target ISP header. And when programming parts
in the red sockets, use the red SPROG3 target ISP header.Table 3-2 shows which
socket suits which AVR device, and which SPROG target ISP header to use for ISP
programming.
The 6-wire cables should be connected directly from the ISP6PIN header to the correct
SPROG target ISP header. The cable should not be twisted. A colored wire on the cable
indicates pin 1. Confirm that this is connected to pin 1 on each of the headers.
When programming 8-pin devices, note the following: Pin 1 is used both as RESET and
as PB5 on some devices (ATtiny11, ATtiny12 and ATtiny15). Pin 1 on the 8-pin sockets
SCKT3400D1 and SCKT3400D1 are connected to PB5. The RESET signal used during
ISP programming is therefore not connected to pin 1 on these sockets. This signal must
be connected by placing a wire between RST and the PORTE header and PB5 on the
PORTB header.
