An Unconventional Loudspeaker System                            Latest change: 2019-01-23

Pin use of microprocessors and messages exchanged in the system.


Table 1: Pin use on the cable between the Control Amplifier and the loudspeakers
I use a standard unscreened ethernet cable (UTP).

Pin
Wire color
Function
Remark
2
or + audio signal
1
or/wt - audiosignal
6
gn +5V switches mains power.
Initially feeds the Arduino on the FLT board.
3
gn/wt 0V, GND

4
bl TX+  from control amplifier to loudspeaker, RS422.
A.o. adjustment of Bass and Mid-range volume.
5
bl/wt TX-, RS422.
8
bn RX+ from loudspeaker to control amplifier, RS422. A.o. error messages from power amplifiers.
7
bn/wt RX-, RS422.



Table 2: Pin / port use Arduino Mega 2560 with Ethernet Shield in the Control Amplifier.
Port
Pin , Function
type
Remark
PA0 .. PA7
pin 22 .. 29  to Selector PCB
out
Low = select,
1 bit at a time
PC0 .. PC3
pin 37 .. 34 via SN 74441 to Nixie
out
digits 1 .. 8
PC4 .. PC7
pin 33 .. 30 Input from IR receiver
in
0 .. 10
PG0
pin 41 SCL for PGA print
out

PG1
pin 40 SDA for PGA pcb
out
PGA's are daisy-chained
PG2
pin 39  /CS voor PGA pcb
out

PD0, PD1
pin 21, 20: interrupts from channel selection switch
in
Quadrature switch
PJ0
pin RX3: 50 Hz input mainsOK detection
in
100 Hz interrupts
PJ1 pin TXD3 SpeakerSwitch
in
low = on, internal pullup
PK6
pin A14: Speaker Power
out
low =on, via PNP
PK7
pin A15: Interrupt from IR
in

PK0
pin A8: potmeter Volume Loudspeakers
analog in

PK1
pin A9: potmeter Volume Headphone
analog in

PD2
pin 19: RXD1 from right loudspeaker
in

PD3
pin 18: TXD1 to right loudspeaker
out

PH0
pin 17: RXD2 from left loudspeaker in

PH1
pin 16: TXD2 to left loudspeaker out

PL0, 2, 4
pin 45, 47, 49: motor Volume potmeter
out, parallel
motor takes ca. 50 mA
PL1, 3, 5
pin 44, 46, 48: motor Volume potmeter
out, parallel
motor takes ca. 50 mA
PL6
pin 43: Led Error indicator Left loudspeaker
out
active low
PL7
pin 42: Led Error indicator Right loudspeaker
out
active low



Table 3: Pin / port use Arduino Nano on FLT board
Port
Pin , Doel
type
Remark
PD0
TXD to Control Amplifier
out

PD1
RXD from Control Amplifier
in

PD2
pin D2 MainsOK, 50 Hz squarewave
in internal pullup
PD3
pin D3 Crydom +5V from Control Amplifier
in
PD4
pin D4 determine FLT or TestTool
out low = FLT, internal pullup
PD5
pin D5 ERR led active low
out
PD6
pin D6 COM led active low out blinks at message rate
PD7
pin D7 CPU led active low
out slow blink = ok
PB0
pin D8 Fault from TPA-Bass
in
active low
PB1
pin D9 Clip-OTW from TPA-Bass
in, intr
clip counter, OTW= perm low
PB2
pin D10 Fault from TPA Mid-Tweeter
in
active low
PB3
pin D11 Clip-OTW from TPA Mid-Tweeter
in, intr
clip counter, OTW = perm low
PB4
pin D12 RST to both TPA's
out low = reset
PB5
pin Led on board Arduina Nano
NC
PC0 pin A0 SCL for PGA
out
PC1
pin A1 SDA for PGA
out
PC2
pin A2 CS for PGA
out
PC3
pin A3 2.5 Volt reference
in, analog
PC4
pin A4 V50
in, analog

PC5
pin A5 V5
in, analog

PC6
pin A6 V12
in, analog

PC7
pin A7 Vmin5
in, analog




Messages between GUI, Control Amplifier and Loudspeakers (FLT board).

Table 4: Message from Control Amplifier to Loudspeaker (FLT), 3 bytes:
This message is sent only when enabled in the GUI
Type: Serial. In the Control Amplifier TX2 for left, TX1 for right.
Remark: When communication stops for more than 2 seconds the arduino on the FLT board goes in Local mode.
Remark: In Pascal (GUI) the bytes are numbered from 1 up, in C (Arduino) bytes are numbered from 0 up.
Remark: 2-byte integers are in little endian.

Byte
C
Byte
Pascal
Name
Range / meaning
Remark
0
1
Command
bit 0: not used
bit 1: not used
bit 2: Write values to EEPROM
bit 3: not used
bit 4: Power ON
bit 5: Clear Clipcounter B
bit 6: Clear Clipcounter MT
bit 7: Reset TPA chips




TestTool only

1
2
Code Bass
Code for PGA. 192 = 0dB gain

2
3
Code Middden
Code for PGA. 192 = 0dB gain


Table 5: Message from Loadspeaker (FLT) to Control Amplifier, 13 bytes.
This message is sent as a reaction on an incoming message and / or when the error code <> 0, 2 times per second.
Type: serial. In Control Amplifier via Rx2 for left, Rx1 for right.

Byte
C
Byte
Pascal
Name
Range / meaning Remark
0
1
Status
Bit 0: Mains Fail
Bit 1: Supply out of range
Bit 2: Fault B
Bit 3: Fault MT
Bit 4: OTW B
Bit 5: OTW MT
Bit 6: Spontaneous message
Bit 7: TPA is in Reset







1, 2
2, 3
VRef raw
ADC value

3, 4
4, 5
V50 raw
ADC value
5, 6
6, 7
V12 raw
ADC value
7, 8 8, 9
V5 raw
ADC value

9, 10
10, 11
Vmin5 raw
ADC value

11
12
ClipCount B
byte

12
13
ClipCount MT
byte



Table 6: Message from GUI_ConfigTool (PC program) to Control Amplifier, 15 bytes:
Type: UDP over ETH.
Byte
C
Byte
Pascal
Naam
Range / meaning Remark
0
1
Command
bit 0: Talk to the Speakers
bit 1: Enable Speaker Power
bit 2: not used
bit 3: not used
bit 4: not used
bit 5: not used
bit 6: Reset Left Loudspeaker
bit 7: Reset Right Loudspeaker

1
2
channel 1
code for PGA  192 = 0dB gain
2
3
channel 2 code for PGA
3
4
channel 3 code for PGA
4
5
channel 4 code for PGA
5
6
channel 5 code for PGA
6
7
channel 6 code for PGA
7
8
channel 7 code for PGA
8
9
channel 8 code for PGA
9
10
Effect code for PGA correctionop Effect left and right
10
11
Centrum code for PGA correction on Centrum
11
12
Extra code for PGA correction on extra channel

12
13
Command Spkr Left
See table 4

13
14
Command Spkr Right
See table 4
14
15
FLT Bass code for PGA
15
16
FLT Mid-range code for PGA



Table 7: Message from Control Amplifier to GUI_ConfigTool (PC program)
This message is sent as reaction on an incoming message.
Type: UDP over ETH.
Remark: The messages from the loudspeakers (FLT) go as-is into this message.


Byte
C
Byte
Pascal
Name
Range / meaning Remark
0
1
Firmware Version number
byte

1
2
Actual selected channel


2
3
Latest IR code


3
4
Volume potmeter Loudspeakers
raw ADC value

4
5
Volume potmeter Headphone
raw ADC value

5
6
Status Loudspeaker Left
See table 5
Message from spkr is copied as is
6, 7
7, 8
Vref  See table 5
8, 9
9, 10
V50
See table 5
10, 11
11, 12
V12
See table 5
12, 13
13, 14
V+5A  See table 5
14, 15
15, 16
V-5A  See table 5
16
17
ClipCountB
See table 5
17
18
ClipCountMT
See table 5
18
19
Status Loudspeaker Right
See table 5 Message from spkr is copied as is
19, 20
20, 21
Vref  See table 5
21, 22
22, 23
V50
See table 5
23, 24
24, 25
V12
See table 5
25, 26
26, 27
V+5A
See table 5
27, 28
28, 29
V-5A
See table 5
29
30
ClipCountB 
See table 5
30
31
ClipCountMT
See table 5



Table 8: Leds on the FLT-board.

Error
Blue (mainsOK)
Yellow (Communication)
Red (Error)
Reset TPA
None
slow blink
off
off
off
Fault Bass
slow blink slow blink
slow blink
reset
Fault Midrange
slow blink slow blink fast blink
reset
OTW Bass
slow blink slow blink off
off
OTW MT
slow blink slow blink off
off
Mains Fail
fast blink slow blink off
reset
Supply fail
slow blink slow blink on
reset
Clip Bass
slow blink slow blink off
off
Clip MT
slow blink slow blink off
off
Control Amplifier Talks
slow blink fast blink
off
off