fuse | default | meaning | page |
RSTDISBL | 1 | Reset disable =0, pin becomes PB7, further programming requires parallel mode programmer | 108 |
CKSEL3..0 | 0001 | internal, external, ceramic, RC, crystal | 24,27 |
PLLCK | 1 | adds an internal 64MHz PLL for use between 4.5 and 5.5V, Systemclock will be 16MHz then | 24,30 |
CKOPT | 1 | clock amplifier for crystal oscillator or so, depends on the clocksource itself, CKOPT=0 for higher amplitudes | 25 |
SUT1..0 | 10 | startup time selector | 26,27,28,29,30 |
SPIEN | 0 | enable SPI programming mode | 108 |
JTAGEN | 0 | enable JTAG programming | 254 |
EESave | 1 | preserve EEPROM through chip erase | 108 |
BODLEVEL | 1 | brownout detection on 2.7V = 1, or 4.0V = 0 | 35,37 |
BODEN | 1 | brownout detection enabled = 0, hysteresis will be 50mV | 37 |
Device clocking option | PLLCK | CKSEL3..0 |
External crystal/ceramic resonator | 1 | 1111-1010 |
External low frequency crystal | 1 | 1001 |
External RC | 1 | 1000-0101 |
Calibrated internal RC | 1 | 0100-0001 |
External clock | 1 | 0000 |
PLL Clock | 0 | 0001 |
CKSEL3..1 | freq range MHZ | recommended caps |
101 | 0.4 - 0.9 | for resonators only |
110 | 0.9 - 3.0 | 12 - 22pF |
111 | 3.0 - 16.0 | 12 - 22pF |
111 | 16 - | 12 - 15pF |
CKOPT | CKSEL0 | SUT1..0 | startup time | additional reset delay | recommended usage |
1 | 0 | 00 | 258 clk | 4.1ms | ceramic, fast rising power, not frequency stable at startup |
1 | 0 | 01 | 258 clk | 65ms | ceramic, slow rising power, not frequency stable at startup |
1 | 0 | 10 | 1k clk | - | ceramic, BOD enabled, frequency stable at startup |
1 | 0 | 11 | 1k clk | 4.1ms | ceramic, fast rising power, frequency stable at startup |
1 | 1 | 00 | 1k clk | 65ms | ceramic, slow rising power, frequency stable at startup |
x | 1 | 01 | 16k clk | - | crystal, BOD enabled |
x | 1 | 10 | 16k clk | 4.1ms | crystal, fast rising power |
x | 1 | 11 | 16k clk | 65ms | crystal, slow rising power |
SUT1..0 | Startup from powerdown & powersave | additionaldelayfrom reset @ Vcc=5V | recommended usage |
00 | 1k clk | 4.1ms | fast rising power or BOD enabled |
01 | 1k clk | 65ms | slowly rising power |
10 | 32k clk | 65ms | Stable frequency at startup |
11 | reserved | reserved | reserved |
CKSEL3..0 | Nominal frequency |
0101 | <= 0.9 MHz |
0110 | 0.9 - 3.0 MHz |
0111 | 3.0 - 8.0 MHz |
1000 | 8.0 - 12.0 MHz |
SUT1..0 | Startup from powerdown & powersave | additionaldelayfrom reset @ Vcc=5V | recommended usage |
00 | 18clk | - | BOD enabled |
01 | 18clk | 4.1ms | fast rising power |
10 | 18clk | 65ms | Slowly rising power |
11 | 6clk | 4.1ms | fast rising power or BOD enabled |
CKSEL3..0 | Nominal frequency |
0001 | 1.0 MHz |
0010 | 2.0 MHz |
0011 | 4.0 MHz |
0100 | 8.0 MHz |
SUT1..0 | Startup from powerdown & powersave | additionaldelayfrom reset @ Vcc=5V | recommended usage |
00 | 6clk | - | BOD enabled |
01 | 6clk | 4.1ms | fast rising power |
10 | 6clk | 65ms | Slowly rising power |
11 | reserved | reserved | reserved |
OSCCAL value | min frequency in percentage from nominal | max frequency in percentage from nominal |
$00 | 50 | 100 |
$7F | 75 | 150 |
$FF | 100 | 200 |
SUT1..0 | Startup from powerdown & powersave | additionaldelayfrom reset @ Vcc=5V | recommended usage |
00 | 6clk | - | BOD enabled |
01 | 6clk | 4.1ms | fast rising power |
10 | 6clk | 65ms | Slowly rising power |
11 | reserved | reserved | reserved |
SUT1..0 | Startup from powerdown & powersave | additionaldelayfrom reset @ Vcc=5V | recommended usage |
00 | 1k CK | - | BOD enabled |
01 | 1k CK | 4.1ms | fast rising power |
10 | 1k CK | 65ms | Slowly rising power |
11 | 16k CK | - | slowly rising power |