Difference between revisions of "ACU Real Time Clock (DIY)"
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ACU Real Time Clock, DIY from magazine "Amstrad User April 85". | ACU Real Time Clock, DIY from magazine "Amstrad User April 85". | ||
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| + | * The RTC chip doesn't include a Year register (aside from the leap-year shift register, but it can span only 4 years, and it is write-only). | ||
== Technical == | == Technical == | ||
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F Interrupt (R/W) | F Interrupt (R/W) | ||
Registers 1..C are BCD (range 0..9), a value of 0Fh in these registers indicates Failure. | Registers 1..C are BCD (range 0..9), a value of 0Fh in these registers indicates Failure. | ||
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== Article == | == Article == | ||
Revision as of 16:33, 9 January 2010
ACU Real Time Clock, DIY from magazine "Amstrad User April 85".
- The RTC chip doesn't include a Year register (aside from the leap-year shift register, but it can span only 4 years, and it is write-only).
Technical
Uses a Z80 PIO, MM58174 RTC, 6116 (2K RAM), 32.768kHz Crystal. Both RTC and RAM are backed by rechargeable 3.6V NiCad battery. Used I/O Ports are (with only A10,A4,A3 decoded):
FBE7 Z80 PIO Data In/Out Port A FBEF Z80 PIO Data In/Out Port B FBF7 Z80 PIO Configure Port A FBFF Z80 PIO Configure Port A
The 4bit RTC Registers are:
0 Not used / Test (W) 1 Seconds 1/10s Fraction (0..9) (R) 2 Seconds LSB (0..9) (R) 3 Seconds MSB (0..5) (R) 4 Minutes LSB (0..9) (R/W) 5 Minutes MSB (0..5) (R/W) 6 Hours LSB (0..9) (R/W) 7 Hours MSB (0..2) (R/W) 8 Day LSB (0..9) (R/W) 9 Day MSB (0..3) (R/W) A Day of Week (1..7) (R/W) B Month LSB (0..9) (R/W) C Month MSB (0..1) (R/W) D Leap Year Shift Register (W) E Stop/Start (W) F Interrupt (R/W)
Registers 1..C are BCD (range 0..9), a value of 0Fh in these registers indicates Failure.
