summaryrefslogtreecommitdiffstatshomepage
path: root/src/devices/machine/upd7004.cpp
blob: ceb54d09acb290a1f72b7a701676fda64d499432 (plain) (blame)
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
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
// license: BSD-3-Clause
// copyright-holders: Dirk Best
/***************************************************************************

    µPD7004

    10-bit 8 Channel A/D Converter

    TODO:
    - Serial modes
    - 2s complement output

***************************************************************************/

#include "emu.h"
#include "upd7004.h"

#define VERBOSE 0
#include "logmacro.h"


//**************************************************************************
//  DEVICE DEFINITIONS
//**************************************************************************

DEFINE_DEVICE_TYPE(UPD7004, upd7004_device, "upd7004", "UPD7004 A/D Converter")

// permit our enum to be saved
ALLOW_SAVE_TYPE(upd7004_device::state);


//**************************************************************************
//  LIVE DEVICE
//**************************************************************************

//-------------------------------------------------
//  upd7004_device - constructor
//-------------------------------------------------

upd7004_device::upd7004_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock) :
	device_t(mconfig, UPD7004, tag, owner, clock),
	m_eoc_cb(*this), m_eoc_ff_cb(*this),
	m_in_cb{ {*this}, {*this}, {*this}, {*this}, {*this}, {*this}, {*this}, {*this} },
	m_state(STATE_IDLE),
	m_cycle_timer(nullptr),
	m_div(1), m_code(false), m_address(0), m_sar(0x3ff)
{
}

//-------------------------------------------------
//  device_start - device-specific startup
//-------------------------------------------------

void upd7004_device::device_start()
{
	// resolve callbacks
	m_eoc_cb.resolve_safe();
	m_eoc_ff_cb.resolve_safe();

	for (int i = 0; i < 8; i++)
		m_in_cb[i].resolve_safe(0x3ff);

	// allocate timers
	m_cycle_timer = timer_alloc();
	m_cycle_timer->adjust(attotime::never);

	// register for save states
	save_item(NAME(m_state));
	save_item(NAME(m_div));
	save_item(NAME(m_code));
	save_item(NAME(m_address));
	save_item(NAME(m_sar));
}

//-------------------------------------------------
//  device_timer - handler timer events
//-------------------------------------------------

void upd7004_device::device_timer(emu_timer &timer, device_timer_id id, int param, void *ptr)
{
	switch (m_state)
	{
		case STATE_IDLE:
			m_cycle_timer->adjust(attotime::never);
			break;

		case STATE_CONVERSION_START:
			m_sar = m_in_cb[m_address](0);

			// the conversion takes 96 to 104 cycles
			m_state = STATE_CONVERSION_DONE;
			m_cycle_timer->adjust(attotime::from_ticks(100, clock() / m_div));

			break;

		case STATE_CONVERSION_DONE:
		{
			// set eoc
			m_eoc_cb(1);
			m_eoc_ff_cb(1);

			m_state = STATE_IDLE;
			m_cycle_timer->adjust(attotime::never);

			LOG("Conversion finished, result: %03x\n", m_sar);

			break;
		}
	}
}


//**************************************************************************
//  INTERFACE
//**************************************************************************

READ8_MEMBER(upd7004_device::read)
{
	uint8_t data = 0xff;

	// connected to a flip-flop, cleared on read
	m_eoc_ff_cb(0);

	switch (offset)
	{
	case 0:
		// low-byte data output
		data = (m_sar & 0x03) << 6;
		break;

	case 1:
		// high-byte data output
		data = (m_sar >> 2) & 0xff;
		break;
	}

	return data;
}

WRITE8_MEMBER(upd7004_device::write)
{
	switch (offset)
	{
	case 0:
		// address set
		m_address = data & 0x07;

		// reset eoc
		m_eoc_cb(0);

		// start conversion timer
		m_state = STATE_CONVERSION_START;
		m_cycle_timer->adjust(attotime::from_hz(clock() / m_div));

		LOG("Select address %d\n", m_address);

		break;

	case 1:
		// initialize
		m_div = 1 << (data & 0x03);
		m_code = data & 0x04;

		logerror("Initialize with clock division ratio %d, %s data\n", m_div, m_code ? "2s complement" : "binary");

		if (m_code)
			logerror("Warning: 2s complement data unimplemented\n");

		break;
	}
}