diff options
Diffstat (limited to 'src/devices/sound/dac76.h')
-rw-r--r-- | src/devices/sound/dac76.h | 91 |
1 files changed, 67 insertions, 24 deletions
diff --git a/src/devices/sound/dac76.h b/src/devices/sound/dac76.h index c9a78c51a19..5f4edbd29f5 100644 --- a/src/devices/sound/dac76.h +++ b/src/devices/sound/dac76.h @@ -1,21 +1,37 @@ -// license: GPL-2.0+ -// copyright-holders: Dirk Best +// license:BSD-3-Clause +// copyright-holders:Dirk Best /*************************************************************************** PMI DAC-76 COMDAC - Companding D/A Converter + Companding Multiplying D/A Converter + + Equivalent to the AM6070, which is an "improved pin-for-pin replacement for + DAC-76" (according to the AM6070 datasheet). ___ ___ - E/D 1 |* u | 10 VLC - SB 2 | | 11 VR+ - B1 3 | | 12 VR- - B2 4 | | 13 V- + E/D 1 |* u | 18 V+ + SB 2 | | 17 IOD- + B1 3 | | 16 IOD+ + B2 4 | | 15 IOE- B3 5 | | 14 IOE+ - B4 6 | | 15 IOE- - B5 7 | | 16 IOD+ - B6 8 | | 17 IOD- - B7 9 |_______| 18 V+ + B4 6 | | 13 V- + B5 7 | | 12 VR- + B6 8 | | 11 VR+ + B7 9 |_______| 10 VLC + + Given: + - Iref = current flowing into VR+ + - X = DAC value, normalized to [-1, 1] + - E/D (pin 1) is low + + The output will be: + - IOD+ = (X > 0) ? (3.8 * Iref * abs(X)) : 0 + - IOD- = (X < 0) ? (3.8 * Iref * abs(X)) : 0 + + The outputs are typically converted to voltages and summed into a single + signal by a current-to-voltage converter (I2V) consisting of an op-amp and + two resistors. ***************************************************************************/ @@ -36,37 +52,64 @@ public: // construction/destruction dac76_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock); + // When streaming is enabled, the Iref will be obtained from the input sound + // stream. Otherwise, the value set with `set_fixed_iref` will be used. + void configure_streaming_iref(bool streaming_iref); + + // By default, the control current (Iref) is treated as normalized ([0, 1], + // defaults to 1), and the sound output is normalized to [-1, 1]. + // + // When in "voltage output" mode, Iref (fixed or streaming) should be the + // current flowing into pin 11, and the output will be a voltage stream. + // `r_pos` is the feedback resistor of the I2V, which is also connected to + // IOD+ (pin 16). + // `r_neg` is the resistor to ground connected to IOD- (pin 17). + // Note that r_pos connects to the "-" input of the I2V op-amp, and r_neg to + // the "+" input. + void configure_voltage_output(float i2v_r_pos, float i2v_r_neg); + + // Reference current. Ignored when streaming Iref mode is enabled. + void set_fixed_iref(float iref); + // chord - DECLARE_WRITE_LINE_MEMBER(b1_w) { m_chord &= ~(1 << 2); m_chord |= (state << 2); }; - DECLARE_WRITE_LINE_MEMBER(b2_w) { m_chord &= ~(1 << 1); m_chord |= (state << 1); }; - DECLARE_WRITE_LINE_MEMBER(b3_w) { m_chord &= ~(1 << 0); m_chord |= (state << 0); }; + void b1_w(int state) { m_chord &= ~(1 << 2); m_chord |= (state << 2); } + void b2_w(int state) { m_chord &= ~(1 << 1); m_chord |= (state << 1); } + void b3_w(int state) { m_chord &= ~(1 << 0); m_chord |= (state << 0); } // step - DECLARE_WRITE_LINE_MEMBER(b4_w) { m_step &= ~(1 << 3); m_step |= (state << 3); }; - DECLARE_WRITE_LINE_MEMBER(b5_w) { m_step &= ~(1 << 2); m_step |= (state << 2); }; - DECLARE_WRITE_LINE_MEMBER(b6_w) { m_step &= ~(1 << 1); m_step |= (state << 1); }; - DECLARE_WRITE_LINE_MEMBER(b7_w) { m_step &= ~(1 << 0); m_step |= (state << 0); }; + void b4_w(int state) { m_step &= ~(1 << 3); m_step |= (state << 3); } + void b5_w(int state) { m_step &= ~(1 << 2); m_step |= (state << 2); } + void b6_w(int state) { m_step &= ~(1 << 1); m_step |= (state << 1); } + void b7_w(int state) { m_step &= ~(1 << 0); m_step |= (state << 0); } // sign bit - DECLARE_WRITE_LINE_MEMBER(sb_w) { m_sb = bool(state); }; + void sb_w(int state) { m_sb = bool(state); } void update() { m_stream->update(); } protected: // device-level overrides - virtual void device_start() override; - virtual void device_reset() override; + virtual void device_start() override ATTR_COLD; + virtual void device_reset() override ATTR_COLD; - virtual void sound_stream_update(sound_stream &stream, stream_sample_t **inputs, stream_sample_t **outputs, int samples) override; + virtual void sound_stream_update(sound_stream &stream) override; private: static constexpr int m_level[8] = { 0, 33, 99, 231, 495, 1023, 2079, 4191 }; sound_stream *m_stream; - uint8_t m_chord; // 4-bit - uint8_t m_step; // 3-bit + // configuration + bool m_streaming_iref; + bool m_voltage_output; + float m_r_pos; + float m_r_neg; + + // state + uint8_t m_chord; // 3-bit + uint8_t m_step; // 4-bit bool m_sb; + float m_fixed_iref; }; // device type definition |