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// license:BSD-3-Clause
// copyright-holders:Michael Zapf
/*
Texas Instruments/Benchmarq BQ4847 Real-time clock
Although featuring a similar interface, this chip is sufficiently
different from the BQ4842/BQ4852 that a separate implementation
makes sense.
Supports 24h/12h and Daylight saving
No internal memory, only clock registers
Michael Zapf, April 2020
*/
#include "emu.h"
#include "bq4847.h"
#define LOG_WARN (1U<<1) // Warnings
#define LOG_CLOCK (1U<<2) // Clock operation
#define LOG_REGW (1U<<3) // Register write
#define LOG_WATCHDOG (1U<<4) // Watchdog
#define VERBOSE ( LOG_GENERAL | LOG_WARN )
#include "logmacro.h"
// device type definition
DEFINE_DEVICE_TYPE(BQ4847, bq4847_device, "bq4847", "Benchmarq BQ4847 RTC")
enum
{
reg_seconds = 0, // 0x00 - 0x59
reg_alarmseconds, // 0xc0 to ignore
reg_minutes, // 0x00 - 0x59
reg_alarmminutes, // 0xc0 to ignore
reg_hours, // 0x00 - 0x23 (24h) or 0x81 - 0x92 (12h)
reg_alarmhours, // 0xc0 to ignore
reg_date, // 0x01 - 0x31
reg_alarmdate, // 0xc0 to ignore
reg_days, // 0x01 (sun) - 0x07 (sat)
reg_month, // 0x01 - 0x12
reg_year, // 0x00 - 0x99
reg_rates, // 0 [--WD--] [-----RS---------]
reg_interrupts, // 0 0 0 0 AIE PIE PWRIE ABE 0x00 on powerup
reg_flags, // 0 0 0 0 AF PF PWRF BVF 0x00 after reading
reg_control, // 0 0 0 0 UTI STOP 24/12 DSE
reg_unused // 0x00
};
enum
{
FLAG_AIE = 0x08,
FLAG_PIE = 0x04,
FLAG_PWRIE = 0x02,
FLAG_ABE = 0x01,
FLAG_AF = 0x08,
FLAG_PF = 0x04,
FLAG_PWRF = 0x02,
FLAG_BVF = 0x01,
FLAG_UTI = 0x08,
FLAG_STOP = 0x04,
FLAG_24 = 0x02,
FLAG_DSE = 0x01
};
//-------------------------------------------------
// Constructors for basetype
//-------------------------------------------------
bq4847_device::bq4847_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock)
: device_t(mconfig, BQ4847, tag, owner, clock),
device_nvram_interface(mconfig, *this),
m_interrupt_cb(*this),
m_wdout_cb(*this),
m_watchdog_active(false),
m_writing(false)
{
}
bool bq4847_device::increment_bcd(uint8_t& bcdnumber, uint8_t limit, uint8_t min)
{
if (!valid_bcd(bcdnumber, min, limit))
{
bcdnumber = min;
return false;
}
if (bcdnumber==limit)
{
bcdnumber = min;
return true;
}
else
{
uint8_t dig0 = bcdnumber & 0x0f;
uint8_t dig1 = bcdnumber & 0xf0;
if (dig0==9)
{
bcdnumber = dig1 + 0x10;
}
else bcdnumber++;
}
return false;
}
bool bq4847_device::valid_bcd(uint8_t value, uint8_t min, uint8_t max)
{
bool valid = ((value>=min) && (value<=max) && ((value&0x0f)<=9));
if (!valid) LOGMASKED(LOG_WARN, "Invalid BCD number %02x\n", value);
return valid;
}
uint8_t bq4847_device::to_bcd(uint8_t value)
{
return (((value / 10) << 4) & 0xf0) | (value % 10);
}
uint8_t bq4847_device::from_bcd(uint8_t value)
{
return ((value & 0xf0)>>4)*10 + (value & 0x0f);
}
// ----------------------------------------------------
/*
Update cycle, called every second
The BQ RTCs use BCD representation
*/
TIMER_CALLBACK_MEMBER(bq4847_device::rtc_clock_cb)
{
// BCD-encoded numbers
static const int days_in_month_table[12] =
{
0x31,0x28,0x31, 0x30,0x31,0x30,
0x31, 0x31, 0x30, 0x31, 0x30, 0x31
};
// Just for debugging
static const char* dow[7] = { "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" };
bool carry = true;
bool newsec = false;
if (carry)
{
carry = increment_bcd(m_intreg[reg_seconds], 0x59, 0);
newsec = true;
}
if (carry)
carry = increment_bcd(m_intreg[reg_minutes], 0x59, 0);
if (carry)
{
// Handle DST
if (is_set(reg_control, FLAG_DSE)
&& (m_reg[reg_month]==4) && (m_reg[reg_days]==0) && (m_reg[reg_date] < 8) // first Sunday in April
&& (m_reg[reg_hours]==0x01))
m_reg[reg_hours] = 0x03;
else
{
if (!is_set(reg_control, FLAG_DSE)
|| (m_reg[reg_month]!=10) || (m_reg[reg_days]!=0) || (m_reg[reg_date] <= 23) // last Sunday in October
|| (m_reg[reg_hours]!=0x01))
carry = increment_bcd(m_intreg[reg_hours], 0x23, 0);
}
}
if (carry)
{
uint8_t month = m_intreg[reg_month];
if (!valid_bcd(month, 0x01, 0x12)) month = 1;
uint8_t days = days_in_month_table[month-1];
// Are leap years considered?
if ((month==2)
&& ((m_intreg[reg_year]%4)==0)
&& ((m_intreg[reg_year]%100)!=0
|| (m_intreg[reg_year]%400)==0))
days = 0x29;
increment_bcd(m_intreg[reg_days], 7, 1);
carry = increment_bcd(m_intreg[reg_date], days, 1);
}
if (carry)
carry = increment_bcd(m_intreg[reg_month], 0x12, 1);
if (carry)
carry = increment_bcd(m_intreg[reg_year], 0x99, 0);
LOGMASKED(LOG_CLOCK, "%s 20%02x-%02x-%02x %02x:%02x:%02x\n",
dow[m_intreg[reg_days]-1], m_intreg[reg_year], m_intreg[reg_month], m_intreg[reg_date],
m_intreg[reg_hours], m_intreg[reg_minutes], m_intreg[reg_seconds]);
// Copy into memory registers if the read bit is reset
if (newsec)
{
if (!is_set(reg_control, FLAG_UTI))
{
// Copy values from internal registers to accessible registers
transfer_to_access();
}
if (check_match(reg_date, reg_alarmdate) &&
check_match(reg_hours, reg_alarmhours) &&
check_match(reg_minutes, reg_alarmminutes) &&
check_match(reg_seconds, reg_alarmseconds))
{
set_register(reg_flags, FLAG_AF, true);
m_interrupt_cb(intrq_r());
}
}
}
bool bq4847_device::check_match(int now, int alarm)
{
// The ignore feature is active once the alarm has set in
// Will lead to a periodic alarm
bool ignore = (is_set(m_reg[alarm], 0x80) && is_set(m_reg[alarm], 0x40)) && is_set(reg_flags, FLAG_AF);
return ignore || (m_intreg[now] == (m_reg[alarm] & 0x3f));
}
// =========================================================
/*
Read from registers
*/
uint8_t bq4847_device::read(offs_t address)
{
int regnum = address & 0x0f;
uint8_t value = m_reg[regnum];
if (regnum == reg_flags)
{
set_register(reg_flags, 0xff, false);
m_interrupt_cb(intrq_r());
}
return value;
}
/*
Write to the registers
*/
void bq4847_device::write(offs_t address, uint8_t data)
{
int regnum = address & 0x0f;
if (regnum == reg_flags)
{
LOGMASKED(LOG_WARN, "Ignoring write attempt to flag bit register (%02x)\n", data);
return;
}
m_reg[regnum] = data;
if (regnum == reg_rates)
{
set_watchdog_timer(true);
set_periodic_timer();
}
else
{
if (regnum == reg_control)
{
// After we have written to the registers, transfer to the internal regs
if (is_set(reg_control, FLAG_UTI) && ((data & FLAG_UTI)==0) && m_writing)
transfer_to_int();
// We ignore the STOP* flag, since it only covers behaviour on power-off
// We ignore the 24h/12h flag here; it requires reloading the registers anyway
// The DSE flag will have effect on update
}
else
m_writing = true;
}
}
void bq4847_device::set_register(int number, uint8_t bits, bool set)
{
if (set)
m_reg[number] |= bits;
else
m_reg[number] &= ~bits;
}
uint8_t bq4847_device::ampmto24(uint8_t ampm)
{
uint8_t f24 = from_bcd(ampm);
if (f24==12) f24 = 0;
else
{
if (ampm & 0x80)
{
if (f24 == 92)
f24 = 12;
else
f24 = f24 - 68;
}
}
return to_bcd(f24);
}
uint8_t bq4847_device::ampmfrom24(uint8_t f24)
{
uint8_t ampm = from_bcd(f24);
if (ampm==0)
ampm = 12;
else
{
if (ampm == 12)
ampm = 92;
else
{
if (ampm > 12)
ampm = ampm + 68;
}
}
return to_bcd(ampm);
}
bool bq4847_device::is_set(int number, uint8_t flag)
{
return (m_reg[number] & flag)!=0;
}
void bq4847_device::transfer_to_int()
{
m_intreg[reg_year] = m_reg[reg_year];
m_intreg[reg_month] = m_reg[reg_month];
m_intreg[reg_date] = m_reg[reg_date];
m_intreg[reg_days] = m_reg[reg_days];
m_intreg[reg_minutes] = m_reg[reg_minutes];
m_intreg[reg_seconds] = m_reg[reg_seconds];
// Check: What is the real device's behavior on inconsistent time formats?
if (is_set(reg_control, FLAG_24))
m_intreg[reg_hours] = m_reg[reg_hours];
else
m_intreg[reg_hours] = ampmto24(m_reg[reg_hours]);
}
void bq4847_device::transfer_to_access()
{
m_reg[reg_year] = m_intreg[reg_year];
m_reg[reg_month] = m_intreg[reg_month];
m_reg[reg_date] = m_intreg[reg_date];
m_reg[reg_days] = m_intreg[reg_days];
m_reg[reg_minutes] = m_intreg[reg_minutes];
m_reg[reg_seconds] = m_intreg[reg_seconds];
// Convert to AM/PM if selected
if (is_set(reg_control, FLAG_24))
m_reg[reg_hours] = m_intreg[reg_hours];
else
m_reg[reg_hours] = ampmfrom24(m_intreg[reg_hours]);
// Clear the flag
m_writing = false;
}
void bq4847_device::set_periodic_timer()
{
uint8_t rateval = m_reg[reg_rates] & 0x0f;
int rate = 1<<(16-rateval);
if (rateval == 0)
m_periodic_timer->reset();
else
m_periodic_timer->adjust(attotime::from_hz(rate), 0, attotime::from_hz(rate));
}
void bq4847_device::set_watchdog_timer(bool on)
{
int val = (m_reg[reg_rates] & 0x70)>>4;
// val = 0 -> 1.5 sec
// val = 1 -> 3/128 sec
// val = 2 -> 3/64 sec
// ...
// val = 6 -> 3/4 sec
// val = 7 -> 3 sec
s64 time = 250000000L; // 250 ms
if (val > 0)
{
time <<= 1;
if (val < 7)
time = time / (4<<(6-val));
}
if (on) time *= 6; // delay to on is 6 times the delay to off
if (m_watchdog_active)
m_watchdog_timer->adjust(attotime::from_nsec(time)); // single shot
}
void bq4847_device::set_watchdog_active(bool active)
{
m_watchdog_active = active;
}
void bq4847_device::retrigger_watchdog()
{
m_wdout_cb(CLEAR_LINE);
m_watchdog_asserted = false;
set_watchdog_timer(true);
}
/*
Periodic cycle (called at defined intervals)
*/
TIMER_CALLBACK_MEMBER(bq4847_device::rtc_periodic_cb)
{
set_register(reg_flags, FLAG_PF, true);
if (intrq_r())
m_interrupt_cb(ASSERT_LINE);
}
/*
Watchdog callback (BQ4847)
*/
TIMER_CALLBACK_MEMBER(bq4847_device::rtc_watchdog_cb)
{
if (m_watchdog_active)
{
m_wdout_cb(m_watchdog_asserted? CLEAR_LINE : ASSERT_LINE);
set_watchdog_timer(!m_watchdog_asserted);
m_watchdog_asserted = !m_watchdog_asserted;
LOGMASKED(LOG_WATCHDOG, "Watchdog %s\n", m_watchdog_asserted? "asserted" : "cleared");
}
}
READ_LINE_MEMBER(bq4847_device::intrq_r)
{
bool alarm = is_set(reg_interrupts, FLAG_AIE) && is_set(reg_flags, FLAG_AF);
bool period = is_set(reg_interrupts, FLAG_PIE) && is_set(reg_flags, FLAG_PF);
// We ignore interrupts from power fail or battery low
return (alarm || period)? ASSERT_LINE : CLEAR_LINE;
}
void bq4847_device::connect_osc(bool conn)
{
if (conn)
{
// The internal update cycle is 1 sec
m_clock_timer->adjust(attotime::from_seconds(1), 0, attotime::from_seconds(1));
set_periodic_timer();
}
else
{
// Turn off completely
m_clock_timer->reset();
m_watchdog_timer->reset();
m_periodic_timer->reset();
}
}
void bq4847_device::get_system_time()
{
// Set time from system time
// We always use 24h internally
system_time systime;
machine().current_datetime(systime);
m_intreg[reg_hours] = to_bcd(systime.local_time.hour);
m_intreg[reg_minutes] = to_bcd(systime.local_time.minute);
m_intreg[reg_seconds] = to_bcd(systime.local_time.second);
m_intreg[reg_year] = to_bcd(systime.local_time.year%100);
m_intreg[reg_month] = to_bcd(systime.local_time.month+1);
m_intreg[reg_date] = to_bcd(systime.local_time.mday);
m_intreg[reg_days] = to_bcd(systime.local_time.weekday+1);
set_register(reg_control, FLAG_DSE, systime.local_time.is_dst);
}
void bq4847_device::device_start()
{
m_clock_timer = machine().scheduler().timer_alloc(timer_expired_delegate(FUNC(bq4847_device::rtc_clock_cb), this));
// Periodic timer
m_periodic_timer = machine().scheduler().timer_alloc(timer_expired_delegate(FUNC(bq4847_device::rtc_periodic_cb), this));
// Watchdog timer
m_watchdog_timer = machine().scheduler().timer_alloc(timer_expired_delegate(FUNC(bq4847_device::rtc_watchdog_cb), this));
// Interrupt line
m_interrupt_cb.resolve_safe();
// Watchdog output
m_wdout_cb.resolve_safe();
// Interrupt enables are cleared on powerup
set_register(reg_interrupts, 0xff, false);
// State save
save_pointer(NAME(m_reg), 16);
save_pointer(NAME(m_intreg), 16);
// Start clock
get_system_time();
connect_osc(true);
}
// ----------------------------------------------------
void bq4847_device::nvram_default()
{
std::fill_n(m_reg, 16, 0);
}
void bq4847_device::nvram_read(emu_file &file)
{
file.read(m_reg, 16);
get_system_time();
transfer_to_access();
// Clear the saved flags
set_register(reg_flags, 0xff, false);
// Interrupts must be re-enabled on power-up
set_register(reg_interrupts, 0xff, false);
}
void bq4847_device::nvram_write(emu_file &file)
{
transfer_to_access();
file.write(m_reg, 16);
}
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