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// license:BSD-3-Clause
// copyright-holders:Fabio Priuli,Philip Bennett
/*****************************************************************************
Fujitsu MB87078 6-bit, 4-channel electronic volume controller emulator
An excerpt from the datasheet about the chip functionality:
"A digital signal input controls gain every 0.5 dB step from 0dB to -32dB.
- Gain variable range: 0 dB to -32 dB by 0.5dB or -infinity
- Gain variable range is expanded to connect two channels serially (0 dB to -64 dB)
- Each channel gain can be set respectively
- Test function is provided (to confirm internal data)
- Data is initialized by reset signal (all channels are set to 0dB)
- Logic I/O is TTL comatible"
There are 6 digital data input/output pins and DSEL pin that selects
the group (there are two) of internal registers to be read/written.
Group 0 is 6-bit gain latch
Group 1 is 5-bit control latch (2-bits are channel select and 3-bits are volume control)
Digital I/O Setting:
/TC DSEL D0 D1 D2 D3 D4 D5 I/O MODES (when /TC==H ->write)
H H DSC1 DSC2 EN C0 C32 X Input mode
H L GD0 GD1 GD2 GD3 GD4 GD5 (set)
L H DSC1 DSC2 EN C0 C32 L Output mode
L L GD0 GD1 GD2 GD3 GD4 GD5 (check)
Channel Setting:
DSC2 DSC1 CHANNEL
L L 0
L H 1
H L 2
H H 3
Electrical Volume Setting:
DATA* GAIN
GD5 GD4 GD3 GD2 GD1 GD0 EN C0 C32 (dB)
1 1 1 1 1 1 1 0 0 0
1 1 1 1 1 0 1 0 0 -0.5
1 1 1 1 0 1 1 0 0 -1
1 1 1 1 0 0 1 0 0 -1.5
1 1 1 0 1 1 1 0 0 -2
[..........................................]
0 0 0 0 0 1 1 0 0 -31
0 0 0 0 0 0 1 0 0 -31.5
X X X X X X 1 X 1 -32
X X X X X X 1 1 0 0
X X X X X X 0 X X -infinity
X=don't care
* When reset, DATA is set to 0 dB (code 111111 100)
MB87078 pins and assigned interface variables/functions
/[ 1] D0 /TC [24]
| [ 2] D1 /WR [23]
MB87078_data_w()| [ 3] D2 /CE [22]
MB87078_data_r()| [ 4] D3 DSEL [21]-MB87078_data_w()/data_r() parameter
| [ 5] D4 /RESET [20]-MB87078_reset_comp_w()
\[ 6] D5 /PD [19]
[ 7] DGND VDD [18]
[ 8] AGND 1/2 VDD [17]
[ 9] AIN0 AOUT3 [16]
[10] AOUT0 AIN3 [15]
[11] AIN1 AOUT2 [14]
[12] AOUT1 AIN2 [13]
*****************************************************************************/
#include "emu.h"
#include "machine/mb87078.h"
static const float mb87078_gain_decibel[66] = {
0.0, -0.5, -1.0, -1.5, -2.0, -2.5, -3.0, -3.5,
-4.0, -4.5, -5.0, -5.5, -6.0, -6.5, -7.0, -7.5,
-8.0, -8.5, -9.0, -9.5,-10.0,-10.5,-11.0,-11.5,
-12.0,-12.5,-13.0,-13.5,-14.0,-14.5,-15.0,-15.5,
-16.0,-16.5,-17.0,-17.5,-18.0,-18.5,-19.0,-19.5,
-20.0,-20.5,-21.0,-21.5,-22.0,-22.5,-23.0,-23.5,
-24.0,-24.5,-25.0,-25.5,-26.0,-26.5,-27.0,-27.5,
-28.0,-28.5,-29.0,-29.5,-30.0,-30.5,-31.0,-31.5,
-32.0, -256.0
};
static const int mb87078_gain_percent[66] = {
100,94,89,84,79,74,70,66,
63,59,56,53,50,47,44,42,
39,37,35,33,31,29,28,26,
25,23,22,21,19,18,17,16,
15,14,14,13,12,11,11,10,
10, 9, 8, 8, 7, 7, 7, 6,
6, 5, 5, 5, 5, 4, 4, 4,
3, 3, 3, 3, 3, 2, 2, 2,
2, 0
};
/*****************************************************************************
DEVICE INTERFACE
*****************************************************************************/
DEFINE_DEVICE_TYPE(MB87078, mb87078_device, "mb87078", "MB87078 Volume Controller")
mb87078_device::mb87078_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock)
: device_t(mconfig, MB87078, tag, owner, clock),
m_channel_latch(0),
m_reset_comp(0),
m_gain_changed_cb(*this)
{
m_gain[0] = m_gain[1] = m_gain[2] = m_gain[3] = 0;
memset(m_latch, 0, sizeof(m_latch));
}
//-------------------------------------------------
// device_start - device-specific startup
//-------------------------------------------------
void mb87078_device::device_start()
{
m_gain_changed_cb.resolve_safe();
save_item(NAME(m_channel_latch));
save_item(NAME(m_reset_comp));
save_item(NAME(m_latch[0]));
save_item(NAME(m_latch[1]));
save_item(NAME(m_gain));
}
//-------------------------------------------------
// device_reset - device-specific reset
//-------------------------------------------------
void mb87078_device::device_reset()
{
m_channel_latch = 0;
/* reset chip */
reset_comp_w(0);
reset_comp_w(1);
}
/*****************************************************************************
IMPLEMENTATION
*****************************************************************************/
#define GAIN_MAX_INDEX 64
#define GAIN_INFINITY_INDEX 65
static int calc_gain_index( int data0, int data1 )
{
//data 0: GD0-GD5
//data 1: 1 2 4 8 16
// c1 c2 EN C0 C32
if (!(data1 & 0x04))
{
return GAIN_INFINITY_INDEX;
}
else
{
if (data1 & 0x10)
{
return GAIN_MAX_INDEX;
}
else
{
if (data1 & 0x08)
{
return 0;
}
else
{
return (data0 ^ 0x3f);
}
}
}
}
void mb87078_device::gain_recalc()
{
int i;
for (i = 0; i < 4; i++)
{
int old_index = m_gain[i];
m_gain[i] = calc_gain_index(m_latch[0][i], m_latch[1][i]);
if (old_index != m_gain[i])
m_gain_changed_cb((offs_t)i, mb87078_gain_percent[m_gain[i]]);
}
}
void mb87078_device::data_w( int data, int dsel )
{
if (m_reset_comp == 0)
return;
if (dsel == 0) /* gd0 - gd5 */
{
m_latch[0][m_channel_latch] = data & 0x3f;
}
else /* dcs1, dsc2, en, c0, c32, X */
{
m_channel_latch = data & 3;
m_latch[1][m_channel_latch] = data & 0x1f; //always zero bit 5
}
gain_recalc();
}
float mb87078_device::gain_decibel_r( int channel )
{
return mb87078_gain_decibel[m_gain[channel]];
}
int mb87078_device::gain_percent_r( int channel )
{
return mb87078_gain_percent[m_gain[channel]];
}
void mb87078_device::reset_comp_w( int level )
{
m_reset_comp = level;
/*this seems to be true, according to the datasheets*/
if (level == 0)
{
m_latch[0][0] = 0x3f;
m_latch[0][1] = 0x3f;
m_latch[0][2] = 0x3f;
m_latch[0][3] = 0x3f;
m_latch[1][0] = 0x0 | 0x4;
m_latch[1][1] = 0x1 | 0x4;
m_latch[1][2] = 0x2 | 0x4;
m_latch[1][3] = 0x3 | 0x4;
}
gain_recalc();
}
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