1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
|
// license:BSD-3-Clause
// copyright-holders:Dirk Best
/***************************************************************************
PMI DAC-76 COMDAC
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 | 18 V+
SB 2 | | 17 IOD-
B1 3 | | 16 IOD+
B2 4 | | 15 IOE-
B3 5 | | 14 IOE+
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.
***************************************************************************/
#ifndef MAME_SOUND_DAC76_H
#define MAME_SOUND_DAC76_H
#pragma once
//**************************************************************************
// TYPE DEFINITIONS
//**************************************************************************
class dac76_device : public device_t, public device_sound_interface
{
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
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
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
void sb_w(int state) { m_sb = bool(state); }
void update() { m_stream->update(); }
protected:
// device-level overrides
virtual void device_start() override ATTR_COLD;
virtual void device_reset() override ATTR_COLD;
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;
// 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
DECLARE_DEVICE_TYPE(DAC76, dac76_device)
#endif // MAME_SOUND_DAC76_H
|