The device has three Fuse bytes. The following tables describe briefly the functionality of all the fuses and how they are mapped into the Fuse bytes. Note that the fuses are read as logical zero, '0', if they are programmed.
Extended Fuse Byte | Bit No. | Description | Default Value |
---|---|---|---|
– | 7 | – | 0 |
– | 6 | – | 0 |
– | 5 | – | 0 |
– | 4 | – | 0 |
CFD | 3 | Disable Clock Failure Detection | 0 (programmed, CFD disable) |
BODLEVEL2(1) | 2 | Brown-out Detector trigger level | 1 (unprogrammed) |
BODLEVEL1(1) | 1 | Brown-out Detector trigger level | 1 (unprogrammed) |
BODLEVEL0(1) | 0 | Brown-out Detector trigger level | 1 (unprogrammed) |
Note: 1. Please refer to Table. BODLEVEL Fuse Coding in System and Reset Characteristics for BODLEVEL Fuse decoding.
High Fuse Byte | Bit No. | Description | Default Value |
---|---|---|---|
OCDEN(1) | 7 | Enable OCD | 1 (unprogrammed, OCD disabled) |
JTAGEN | 6 | Enable JTAG | 0 (programmed, JTAG enabled) |
SPIEN(2) | 5 | Enable Serial Program and Data Downloading | 0 (programmed, SPI prog. enabled) |
WDTON(3) | 4 | Watchdog Timer Always On | 1 (unprogrammed) |
EESAVE | 3 | EEPROM memory is preserved through the Chip Erase | 1 (unprogrammed), EEPROM not reserved |
BOOTSZ1(4) | 2 | Select Boot Size | 0 (programmed) |
BOOTSZ0(4) | 1 | Select Boot Size | 0 (programmed) |
BOOTRST | 0 | Boot Reset vector Enabled | 1 (unprogrammed) |
Low Fuse Byte | Bit No. | Description | Default Value |
---|---|---|---|
CKDIV8(4) | 7 | Divide clock by 8 | 0 (programmed) |
CKOUT(3) | 6 | Clock output | 1 (unprogrammed) |
SUT1 | 5 | Select start-up time | 1 (unprogrammed)(1) |
SUT0 | 4 | Select start-up time | 0 (programmed)(1) |
CKSEL3 | 3 | Select Clock source | 0 (programmed)(2) |
CKSEL2 | 2 | Select Clock source | 0 (programmed)(2) |
CKSEL1 | 1 | Select Clock source | 1 (unprogrammed)(2) |
CKSEL0 | 0 | Select Clock source | 0 (programmed)(2) |
The status of the Fuse bits is not affected by Chip Erase. Note that the Fuse bits are locked if Lock bit1 (LB1) is programmed. Program the Fuse bits before programming the Lock bits.