25.7 Serial Programming Pin Mapping
Table 25-14. Pin Mapping Serial Programming
Symbol
MOSI_A
MISO_A
SCK_A
Pins
PD3
PD2
PD4
I/O
Description
Serial data in
Serial data out
Serial clock
I
O
I
25.8 Parallel Programming
25.8.1 Enter Programming Mode
The following algorithm puts the device in Parallel (High-voltage) > Programming mode:
1. Set Prog_enable pins listed in Table 25-9 on page 260 to “0000”, RESET pin to “0” and VCC to 0V.
2. Apply 4.5 to 5.5V between VCC and GND. Ensure that VCC reaches at least 1.8V within the next 20µs.
3. Wait 20 to 60µs, and apply 11.5 to 12.5V to RESET.
4. Keep the Prog_enable pins unchanged for at least 10µs after the high-voltage has been applied to ensure the
Prog_enable signature has been latched.
5. Wait at least 300µs before giving any parallel programming commands.
6. Exit programming mode by power the device down or by bringing RESET pin to 0V.
If the rise time of the VCC is unable to fulfill the requirements listed above, the following alternative algorithm can be used.
1. Set Prog_enable pins listed in Table 25-9 on page 260 to “0000”, RESET pin to “0” and VCC to 0V.
2. Apply 4.5 to 5.5V between VCC and GND.
3. Monitor VCC, and as soon as VCC reaches 0.9 to 1.1V, apply 11.5 to 12.5V to RESET.
4. Keep the Prog_enable pins unchanged for at least 10µs after the high-voltage has been applied to ensure the
Prog_enable signature has been latched.
5. Wait until VCC actually reaches 4.5 to 5.5V before giving any parallel programming commands.
6. Exit programming mode by power the device down or by bringing RESET pin to 0V.
25.8.2 Considerations for Efficient Programming
The loaded command and address are retained in the device during programming. For efficient programming, the following
should be considered.
●
●
The command needs only be loaded once when writing or reading multiple memory locations.
Skip writing the data value 0xFF, that is the contents of the entire EEPROM (unless the EESAVE Fuse is
programmed) and Flash after a Chip Erase.
●
Address high byte needs only be loaded before programming or reading a new 256 word window in Flash or 256 byte
EEPROM. This consideration also applies to signature bytes reading.
ATmega16/32/64/M1/C1 [DATASHEET]
261
7647O–AVR–01/15
MICROCHIP [ MICROCHIP ]
