121 lines
2.5 KiB
Go
121 lines
2.5 KiB
Go
package component
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import (
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"time"
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)
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/*
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microPD1990ac Serial I/O Calendar Clock IC
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See:
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https://www.semiee.com/file/backup/NEC-D1990.pdf
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Used by the ThunderClock+ real time clock card.
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The 40 bit register has 5 bytes (10 nibbles):
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byte 4:
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month, binary from 1 to 12
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day of week, BCD 0 to 6
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byte 3: day of month, BCD 1 to 31
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byte 2: hour, BCD 0 to 23
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byte 1: minute, BCD 0 to 59
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byte 0: seconds, BCD 0 to 59
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*/
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type MicroPD1990ac struct {
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clock bool // CLK state
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strobe bool // STB state
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command uint8 // C0, C1, C2 command. From 0 to 7
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register uint64 // 40 bit shift register
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}
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const (
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mpd1990commandRegHold = 0
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mpd1990commandRegShift = 1
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mpd1990commandTimeSet = 2
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mpd1990commandTimeRead = 3
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)
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func (m *MicroPD1990ac) In(clock bool, strobe bool, command uint8, dataIn bool) {
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// Detect signal raise
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clockRaise := clock && !m.clock
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strobeRaise := strobe && !m.strobe
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// Update signal status
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m.clock = clock
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m.strobe = strobe
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// On strobe raise, update command and execute if needed
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if strobeRaise {
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m.command = command
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switch m.command {
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case mpd1990commandRegShift:
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// Nothing to do
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case mpd1990commandTimeRead:
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m.loadTime()
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default:
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// Ignore unknown commands (like set time)
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//panic(fmt.Sprintf("PD1990ac command %v not implemented.", m.command))
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}
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}
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// On clock raise, with shift enable, shift the register
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if clockRaise && m.command == mpd1990commandRegShift {
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// Rotate right the 40 bits of the shift register
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lsb := m.register & 1
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m.register >>= 1
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m.register += lsb << 39
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}
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}
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func (m *MicroPD1990ac) Out() bool {
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/*
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if m.command == mpd1990commandRegHold {
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panic("Output on RegHold should be a 1Hz signal. Not implemented.")
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}
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if m.command == mpd1990commandTimeRead {
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panic("Output on RegHold should be a 512Hz signal with LSB. Not implemented.")
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}
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*/
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// Return the LSB of the register shift
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return (m.register & 1) == 1
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}
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func (m *MicroPD1990ac) loadTime() {
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now := time.Now()
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var register uint64
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register = uint64(now.Month())
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register <<= 4
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register += uint64(now.Weekday())
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day := uint64(now.Day())
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register <<= 4
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register += day / 10
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register <<= 4
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register += day % 10
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hour := uint64(now.Hour())
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register <<= 4
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register += hour / 10
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register <<= 4
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register += hour % 10
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minute := uint64(now.Minute())
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register <<= 4
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register += minute / 10
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register <<= 4
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register += minute % 10
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second := uint64(now.Second())
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register <<= 4
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register += second / 10
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register <<= 4
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register += second % 10
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m.register = register
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}
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