Difference between revisions of "ACU Real Time Clock (DIY)"
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FBFF Z80 PIO Configure Port A | FBFF Z80 PIO Configure Port A | ||
The 4bit RTC Registers are: | The 4bit RTC Registers are: | ||
| − | 0 Not used | + | 0 Not used / Test (W) |
| − | 1 Seconds Fraction (R) | + | 1 Seconds 1/10s Fraction (0..9) (R) |
2 Seconds LSB (0..9) (R) | 2 Seconds LSB (0..9) (R) | ||
3 Seconds MSB (0..5) (R) | 3 Seconds MSB (0..5) (R) | ||
| − | 4 Minutes LSB (R/W) | + | 4 Minutes LSB (0..9) (R/W) |
| − | 5 Minutes MSB (R/W) | + | 5 Minutes MSB (0..5) (R/W) |
| − | 6 Hours LSB (R/W) | + | 6 Hours LSB (0..9) (R/W) |
| − | 7 Hours MSB (R/W) | + | 7 Hours MSB (0..2) (R/W) |
| − | 8 Day LSB (R/W) | + | 8 Day LSB (0..9) (R/W) |
| − | 9 Day MSB (R/W) | + | 9 Day MSB (0..3) (R/W) |
| − | A Day of Week (R/W) | + | A Day of Week (1..7) (R/W) |
| − | B Month LSB (R/W) | + | B Month LSB (0..9) (R/W) |
| − | C Month MSB (R/W) | + | C Month MSB (0..1) (R/W) |
D Leap Year Shift Register (W) | D Leap Year Shift Register (W) | ||
E Stop/Start (W) | E Stop/Start (W) | ||
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. | ||
| − | The 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). | + | The 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). |
== Article == | == Article == | ||
Revision as of 16:27, 9 January 2010
ACU Real Time Clock, DIY from magazine "Amstrad User April 85".
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. The 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).
