// license:BSD-3-Clause
// copyright-holders:Raphael Nabet,Sergey Svishchev
/***************************************************************************
mm58174.cpp
National Semiconductor MM58174 Microprocessor Compatible Real Time Clock
Docs:
* <http://www.bitsavers.org/components/national/_appNotes/AN-0359.pdf>
* <ftp://ftp.jameco.com/Archive/Obsolete-TechDocuments/26219.pdf>
Todo:
* data-changed flip-flop
* interrupts, MM58174A (no interrupt ack)
* loss of accuracy after restart
***************************************************************************/
#include "emu.h"
#include "mm58174.h"
enum
{
ctl_clkrun = 0x1, /* clock start/stop (1=run, 0=stop) */
year_leap = 0x8,
int_ctl_rpt = 0x8, /* 1 for repeated interrupt */
int_ctl_dly = 0x7 /* 0 no interrupt, 1 = .5 second, 2=5, 4=60 */
};
DEFINE_DEVICE_TYPE(MM58174, mm58174_device, "mm58174", "National Semiconductor MM58174 RTC")
mm58174_device::mm58174_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock)
: device_t(mconfig, MM58174, tag, owner, clock)
, device_rtc_interface(mconfig, *this)
, m_control(0)
, m_int_ctl(0)
, m_tenths(0)
{
}
//-------------------------------------------------
// device_start - device-specific startup
//-------------------------------------------------
void mm58174_device::device_start()
{
m_rtc_timer = timer_alloc(FUNC(mm58174_device::clock_tick), this);
m_rtc_timer->adjust(attotime::zero, 0, attotime::from_msec(100));
m_interrupt_timer = timer_alloc(FUNC(mm58174_device::scheduler_sync), this);
// register for state saving
save_item(NAME(m_control));
save_item(NAME(m_int_ctl));
save_item(NAME(m_wday));
save_item(NAME(m_months1));
save_item(NAME(m_months2));
save_item(NAME(m_days1));
save_item(NAME(m_days2));
save_item(NAME(m_hours1));
save_item(NAME(m_hours2));
save_item(NAME(m_minutes1));
save_item(NAME(m_minutes2));
save_item(NAME(m_seconds1));
save_item(NAME(m_seconds2));
save_item(NAME(m_tenths));
}
//-------------------------------------------------
// rtc_clock_updated -
//-------------------------------------------------
void mm58174_device::rtc_clock_updated(int year, int month, int day, int day_of_week, int hour, int minute, int second)
{
m_seconds1 = second / 10;
m_seconds2 = second % 10;
m_minutes1 = minute / 10;
m_minutes2 = minute % 10;
m_hours1 = hour / 10;
m_hours2 = hour % 10;
m_wday = day_of_week;
m_days1 = day / 10;
m_days2 = day % 10;
m_months1 = month / 10;
m_months2 = month % 10;
m_years = 1 << (3 - (year & 3));
}
attotime mm58174_device::interrupt_period_table(int val)
{
switch(val)
{
case 0: return attotime::never;
case 1: return attotime::from_msec(500);
case 2: return attotime::from_seconds(5);
case 4: return attotime::from_seconds(60);
default: fatalerror("out of range\n");
}
}
void mm58174_device::update_rtc()
{
set_clock_register(RTC_SECOND, m_seconds1 * 10 + m_seconds2);
set_clock_register(RTC_MINUTE, m_minutes1 * 10 + m_minutes2);
set_clock_register(RTC_HOUR, m_hours1 * 10 + m_hours2);
set_clock_register(RTC_DAY, m_days1 * 10 + m_days2);
set_clock_register(RTC_DAY_OF_WEEK, m_wday);
set_clock_register(RTC_MONTH, m_months1 * 10 + m_months2);
}
uint8_t mm58174_device::read(offs_t offset)
{
int reply = 0;
offset &= 0xf;
switch (offset)
{
case 0x01: /* Tenths of Seconds */
reply = m_tenths;
break;
case 0x02: /* Units Seconds */
reply = m_seconds2;
break;
case 0x03: /* Tens Seconds */
reply = m_seconds1;
break;
case 0x04: /* Units Minutes */
reply = m_minutes2;
break;
case 0x05: /* Tens Minutes */
reply = m_minutes1;
break;
case 0x06: /* Units Hours */
reply = m_hours2;
break;
case 0x07: /* Tens Hours */
reply = m_hours1;
break;
case 0x08: /* Units Days */
reply = m_days2;
break;
case 0x09: /* Tens Days */
reply = m_days1;
break;
case 0x0a: /* Day of Week */
reply = m_wday;
break;
case 0x0b: /* Units Months */
reply = m_months2;
break;
case 0x0c: /* Tens Months */
reply = m_months1;
break;
case 0x0f: /* Clock Setting & Interrupt Registers */
reply = m_int_ctl;
break;
default:
reply = 0;
break;
}
logerror("reg %02x == %02x\n", offset, reply);
return reply;
}
void mm58174_device::write(offs_t offset, uint8_t data)
{
offset &= 0xf;
data &= 0xf;
logerror("reg %02x <- %02x\n", offset, data);
switch (offset)
{
case 0x00: /* Test Mode Register (emulated) */
break;
case 0x01: /* Tenths of Seconds: cannot be written */
break;
case 0x02: /* Units Seconds: cannot be written */
break;
case 0x03: /* Tens Seconds: cannot be written */
break;
case 0x04: /* Units Minutes */
m_minutes2 = data;
update_rtc();
break;
case 0x05: /* Tens Minutes */
m_minutes1 = data;
update_rtc();
break;
case 0x06: /* Units Hours */
m_hours2 = data;
update_rtc();
break;
case 0x07: /* Tens Hours */
m_hours1 = data;
update_rtc();
break;
case 0x08: /* Units Days */
m_days2 = data;
update_rtc();
break;
case 0x09: /* Tens Days */
m_days1 = data;
update_rtc();
break;
case 0x0a: /* Day of Week */
m_wday = data;
update_rtc();
break;
case 0x0b: /* Units Months */
m_months2 = data;
update_rtc();
break;
case 0x0c: /* Tens Months */
m_months1 = data;
update_rtc();
break;
case 0x0d: /* Years Status */
break;
case 0x0e: /* Stop/Start */
if ((m_control & ctl_clkrun) && (!(data & ctl_clkrun))) /* interrupt stop */
m_interrupt_timer->enable(0);
else if ((!(m_control & ctl_clkrun)) && (data & ctl_clkrun)) /* interrupt run */
{
attotime period = interrupt_period_table(m_int_ctl & int_ctl_dly);
m_interrupt_timer->adjust(period, 0, m_int_ctl & int_ctl_rpt ? period : attotime::zero);
}
if (!(data & ctl_clkrun)) /* stopping the clock clears the tenth counter */
m_tenths = 0;
m_control = data;
break;
case 0x0f: /* Interrupt Register */
m_int_ctl = data;
if (m_control & ctl_clkrun) /* interrupt run */
{
attotime period = interrupt_period_table(m_int_ctl & int_ctl_dly);
m_interrupt_timer->adjust(period, 0, m_int_ctl & int_ctl_rpt ? period : attotime::zero);
}
break;
}
}
// Increment RTC clock (timed interrupt every 1/10s)
TIMER_CALLBACK_MEMBER(mm58174_device::clock_tick)
{
if (m_control & ctl_clkrun)
{
if ((++m_tenths) == 10)
{
m_tenths = 0;
advance_seconds();
}
}
}
// TODO: Investigate if this is necessary, or if there's missing functionality from the device.
// Prior to the device_timer removal, m_interrupt_timer was being allocated with the same default ID as m_rtc_timer.
// As there was no interrupt-related logic in the existing device_timer implementation, the only possible thing that
// m_interrupt_timer could possibly do, functionally, is force a scheduler sync by elapsing, and also cause the
// RTC to tick at an erroneous rate.
TIMER_CALLBACK_MEMBER(mm58174_device::scheduler_sync)
{
}