User Manual

AT75C220
142
WD Clock Mode Register
Name: WD_CMR
Access: Read/write
Reset Value:0
• WDCLKS: Clock Selection
• HPCV: High Preload Counter Value
Counter is preloaded when watchdog counter is restarted with bits 0 to 11 set (FFF) and bits 12 to 15 equaling HPCV.
• CKEY: Clock Access Key
Used only when writing WD_CMR. CKEY is read as 0.
0x06E: Write access in WD_CMR is allowed.
Other value: Write access in WD_CMR is prohibited.
WD Control Register
Name: WD_CR
Access: Write-only
• RSTKEY: Restart Key
0xC071 = Watchdog counter is restarted.
Other value = No effect.
31 30 29 28 27 26 25 24
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23 22 21 20 19 18 17 16
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15 14 13 12 11 10 9 8
CKEY
76543210
CKEY – HPCV WDCLKS
WDCLKS Clock Selected
00ACLK/8
01ACLK/32
1 0 ACLK/128
1 1 ACLK/1024
31 30 29 28 27 26 25 24
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23 22 21 20 19 18 17 16
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15 14 13 12 11 10 9 8
RSTKEY
76543210
RSTKEY