// license:BSD-3-Clause // copyright-holders:hap /* Hughes HLCD 0538(A)/0539(A) LCD Driver 0538: 8 rows, 26 columns 0539: 0 rows, 34 columns "LCD" pin can be used in 2 modes, either direct drive, or as an oscillator. In latter case, output frequency is approximately 1/RC. TODO: - the only difference between 0538/0539 is row pins voltage levels? */ #include "emu.h" #include "hlcd0538.h" DEFINE_DEVICE_TYPE(HLCD0538, hlcd0538_device, "hlcd0538", "Hughes HLCD 0538 LCD Driver") DEFINE_DEVICE_TYPE(HLCD0539, hlcd0539_device, "hlcd0539", "Hughes HLCD 0539 LCD Driver") //------------------------------------------------- // constructor //------------------------------------------------- hlcd0538_device::hlcd0538_device(const machine_config &mconfig, device_type type, const char *tag, device_t *owner, u32 clock) : device_t(mconfig, type, tag, owner, clock), m_write_cols(*this), m_write_interrupt(*this) { } hlcd0538_device::hlcd0538_device(const machine_config &mconfig, const char *tag, device_t *owner, u32 clock) : hlcd0538_device(mconfig, HLCD0538, tag, owner, clock) { } hlcd0539_device::hlcd0539_device(const machine_config &mconfig, const char *tag, device_t *owner, u32 clock) : hlcd0538_device(mconfig, HLCD0539, tag, owner, clock) { } //------------------------------------------------- // device_start - device-specific startup //------------------------------------------------- void hlcd0538_device::device_start() { // timer (when LCD pin is oscillator) m_lcd_timer = timer_alloc(FUNC(hlcd0538_device::toggle_lcd), this); attotime period = (clock() != 0) ? attotime::from_hz(2 * clock()) : attotime::never; m_lcd_timer->adjust(period, 0, period); // zerofill m_lcd = 0; m_clk = 0; m_data = 0; m_shift = 0; // register for savestates save_item(NAME(m_lcd)); save_item(NAME(m_clk)); save_item(NAME(m_data)); save_item(NAME(m_shift)); } //------------------------------------------------- // handlers //------------------------------------------------- TIMER_CALLBACK_MEMBER(hlcd0538_device::toggle_lcd) { lcd_w(!m_lcd); } void hlcd0538_device::clk_w(int state) { state = (state) ? 1 : 0; // clock in data on falling edge if (!state && m_clk) m_shift = (m_shift << 1 | m_data) & u64(0x3ffffffff); m_clk = state; } void hlcd0538_device::lcd_w(int state) { state = (state) ? 1 : 0; // transfer to latches on rising edge if (state && !m_lcd) { m_write_cols(0, m_shift); m_shift = 0; } m_lcd = state; // interrupt output follows lcd input m_write_interrupt(state); }