diff options
Diffstat (limited to 'src/devices/machine/mm74c922.cpp')
-rw-r--r-- | src/devices/machine/mm74c922.cpp | 38 |
1 files changed, 20 insertions, 18 deletions
diff --git a/src/devices/machine/mm74c922.cpp b/src/devices/machine/mm74c922.cpp index f49b320b41a..edcf4093e20 100644 --- a/src/devices/machine/mm74c922.cpp +++ b/src/devices/machine/mm74c922.cpp @@ -18,7 +18,7 @@ // DEVICE DEFINITIONS //************************************************************************** -DEFINE_DEVICE_TYPE(MM74C922, mm74c922_device, "mm74c922", "MM74C923 16-Key Encoder") +DEFINE_DEVICE_TYPE(MM74C922, mm74c922_device, "mm74c922", "MM74C922 16-Key Encoder") DEFINE_DEVICE_TYPE(MM74C923, mm74c923_device, "mm74c923", "MM74C923 20-Key Encoder") @@ -34,15 +34,15 @@ DEFINE_DEVICE_TYPE(MM74C923, mm74c923_device, "mm74c923", "MM74C923 20-Key Encod mm74c922_device::mm74c922_device(const machine_config &mconfig, device_type type, const char *tag, device_t *owner, uint32_t clock, int max_y) : device_t(mconfig, type, tag, owner, clock), - m_write_da(*this), - m_read_x(*this), + m_write_da(*this), m_read_x(*this, (1 << max_y) - 1), m_tristate_data(*this, (1 << max_y) - 1), m_cap_osc(0), m_cap_debounce(0), m_max_y(max_y), m_inhibit(false), m_x(0), - m_y(0), m_data(0), - m_da(false), - m_next_da(false), m_scan_timer(nullptr) + m_y(0), + m_data(0), m_next_data(0), + m_da(false), m_next_da(false), + m_scan_timer(nullptr) { } @@ -63,32 +63,29 @@ mm74c923_device::mm74c923_device(const machine_config &mconfig, const char *tag, void mm74c922_device::device_start() { - // resolve callbacks - m_write_da.resolve_safe(); - m_read_x.resolve_all_safe((1 << m_max_y) - 1); - // set initial values change_output_lines(); // allocate timers - m_scan_timer = timer_alloc(); - m_scan_timer->adjust(attotime::zero, 0, attotime::from_hz(50)); + m_scan_timer = timer_alloc(FUNC(mm74c922_device::perform_scan), this); + m_scan_timer->adjust(attotime::zero, 0, attotime::from_hz(500)); // approximate rate from a 100n capacitor // register for state saving save_item(NAME(m_inhibit)); save_item(NAME(m_x)); save_item(NAME(m_y)); save_item(NAME(m_data)); + save_item(NAME(m_next_data)); save_item(NAME(m_da)); save_item(NAME(m_next_da)); } //------------------------------------------------- -// device_timer - handler timer events +// perform_scan - scan the keyboard matrix //------------------------------------------------- -void mm74c922_device::device_timer(emu_timer &timer, device_timer_id id, int param, void *ptr) +TIMER_CALLBACK_MEMBER(mm74c922_device::perform_scan) { change_output_lines(); clock_scan_counters(); @@ -123,6 +120,12 @@ void mm74c922_device::change_output_lines() // active high output m_write_da(m_da ? 1 : 0); } + + // clock data latches + if (m_next_data != m_data) + { + m_data = m_next_data; + } } @@ -156,7 +159,7 @@ void mm74c922_device::detect_keypress() // key released m_inhibit = false; m_next_da = false; - m_data = 0xff; // high-Z + m_next_data = m_tristate_data(); // high-Z LOG("MM74C922 Key Released\n"); } @@ -172,10 +175,9 @@ void mm74c922_device::detect_keypress() m_next_da = true; m_y = y; - m_data = (y << 2) | m_x; + m_next_data = (y << 2) | m_x; - LOG("MM74C922 Key Depressed: X %u Y %u = %02x\n", m_x, y, m_data); - return; + LOG("MM74C922 Key Depressed: X %u Y %u = %02x\n", m_x, y, m_next_data); } } } |