Retasking and Amazon Echo 2nd Generation.
I would like to re-use the parts of a non functioning 2nd Gen Echo (model XC56PY).
In fact I want to throw out the motherboard and replace it with a different board (Pico W perhaps) and then use it as a voice assistant/speaker.
Unfortunately, I’ve damaged the LED/Mic board while probing it with a multimeter (I think I’ve managed to short a couple of solder joints) so I’m at a standstill until I fix it. In the meantime I thought I would share what I have so others can continue.
Overview
The Echo consists of 3 separate parts.
- Amplifier/Power board
- Motherboard
- Mic/LED Board
The amplifier is connected to the motherboard with a 0.5mm pitch 24 pin FFC/FPC cable. The cable itself has multiple pins shorted (ground and power) so the orientation of the cable is important. Obtaining breakout boards for these connectors is fairly easy and cheap.
The Mic/LED board is connected to the motherboard with a 0.3mm pitch 37 pin FFC/FPC cable and, once again, the cable has multiple connectors shorted. Getting breakout boards for this is more difficult and expensive.
Amplifier/Power Board
The amplifier looks to be a Texas Instruments TPA3118D2.
The board provides 3.85v to the motherboard.
So far I haven’t done much investigation of this board.
Mic/LED Board
The above circuit diagram may contain errors.
This has 36 status LEDs (12 x RGB LEDs) controlled by what looks like a Lumissil IS31FL3236A (U6) driver.
It also has 7 microphones connected to what looks like 4 Texas Instruments TLV320ADC3101 (U1,U2.U4,U5) ADCs with embedded mini DSPs.
Both the ADCs and the LED driver are controlled via I2C. The addresses are as follows (assuming I have correctly identified the chips):
| Chip | I2C Address | Notes |
|---|---|---|
| U1 | 0x30 | MK1 and MK2 |
| U2 | 0x32 | MK5 and MK6 |
| U4 | 0x31 | MK3 and MK4 |
| U5 | 0x33 | MK7 |
| U6 | 0x7E | LED Driver |
The FFC/FPC connector has the following pins:
| PIN | NAME | TYPE | Notes |
|---|---|---|---|
| 1 | Unk | Unk | |
| 2 | Unk | Unk | |
| 3 | Unk | Unk | |
| 4 | Unk | Unk | |
| 5 | GND | GND | |
| 6 | SCL | I/O | I2C serial clock |
| 7 | SDA | I/O | I2C serial data |
| 8 | GND | GND | |
| 9 | RESET | I | Reset for U1, U2, U4 and U5. Low to reset |
| 10 | BCLK | ? | Audio data serial bus bit clock. Direction unknown |
| 11 | DOUT | O | Audio serial data bus output (via U101) |
| 12 | WCLK | ? | Audio serial bus word clock. Direction unknown |
| 13 | Unk | Unk | |
| 14 | Unk | Unk | |
| 15 | GND | GND | |
| 16 | MCLK | I | Master clock (U1 only) |
| 17 | ENABLE | I | Enable for U6 (SDB) and U101 (OE) |
| 18 | Unk | Unk | |
| 19 | GND | GND | |
| 20 | Unk | Unk | |
| 21 | Unk | Unk | |
| 22 | Unk | Unk | |
| 23 | GND | GND | |
| 24 | GND | GND | |
| 25 | GND | GND | |
| 26 | GND | GND | |
| 27 | GND | GND | |
| 28 | VCC | VCC | 3.8V for the LED driver |
| 29 | VCC | VCC | 3.8V for the LED driver |
| 30 | GND | GND | |
| 31 | GND | GND | |
| 32 | DVDD | DVDD | 1.8V for U1, U2, U4, U5, U101 |
| 33 | DVDD | DVDD | 1.8V for U1, U2, U4, U5, U101 |
| 34 | GND | GND | |
| 35 | GND | GND | |
| 36 | AVDD | AVDD | 3.3V for U1, U2, U4 and U5 |
| 37 | AVDD | AVDD | 3.3V for U1, U2, U4 and U5 |
Once I’ve repaired my Mic/LED board I plan to capture the configuration for the ADC/DSP chips and determine what the various clock speeds are (WCLK, BCLK and MCLK). It might then be possible to build an actual voice assistant.