Author Topic: Teardown: Amazon Echo Dot 2  (Read 11092 times)

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Online NiHaoMike

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Teardown: Amazon Echo Dot 2
« on: October 22, 2016, 06:15:17 pm »
Shortly after Amazon announced the Echo Dot 2, I wondered if it could be hacked to add S/PDIF output so I ordered one. I received it yesterday and started reverse engineering it.

There's certainly more to it than I expected. Just the mechanical design appears very sophisticated, including a cast aluminum CPU heatsink and a rubber seal to prevent feedback.

The motherboard has been completely redesigned since the first generation, replacing the TI CPU with a Mediatek MT8163V, specs similar to the Raspberry Pi 3. There's a chip marked KMFJ20005A that is obviously a memory chip, but even the capacity seems to be elusive to online searching. The RF transceiver is a MT6625L. What's odd is that based on the datasheet I could find, it seems to have a shared IF path for the Bluetooth and 5GHz Wifi. Maybe there are more shared blocks in the chip than what the block diagram would imply? There's a MT6323 mixed signal chip that handles the power and speaker output, and most crucial to the feasibility of adding S/PDIF, a TLV320DAC3203 I2S DAC.

On the top board, there's the array of 7 microphones, 4 TLV320ADC3101 ADCs, and some mystery ASIC marked R3018. It's clearly handling the LEDs and maybe even interfacing the 4 ADCs?
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Offline Cyberdragon

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Re: Teardown: Amazon Echo Dot 2
« Reply #1 on: October 23, 2016, 03:07:18 am »
Yes, that chip is probably an IO interface for the ADCs too. I don't think they would use a custom chip just to control LEDs when an FPGA or even any old multi-channel PWM driver would work.
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Offline y999999

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Re: Teardown: Amazon Echo Dot 2
« Reply #2 on: November 08, 2016, 12:12:26 pm »
According to http://www.allaboutcircuits.com/news/teardown-tuesday-amazon-echo-dot-v2/ R3018/R3019 is a MCU that controls the LED. I am not sure why they didn't implement the PWM inside an FPGA! The tear down also shows a UL1K

 
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Offline daqq

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Re: Teardown: Amazon Echo Dot 2
« Reply #3 on: November 09, 2016, 06:01:11 pm »
Thanks! That's a LOT of vias around the antennas. Strange that they would go for a such a cable, I would have guessed they would use a board to board connector.
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Offline actbluebe

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Re: Teardown: Amazon Echo Dot 2
« Reply #4 on: May 03, 2017, 07:57:45 pm »
Had anyone any success what an S/PDIF output?
 

Online NiHaoMike

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Re: Teardown: Amazon Echo Dot 2
« Reply #5 on: May 05, 2017, 03:46:25 pm »
I haven't had a chance to try adding the S/PDIF transmitter. I recall the logic is 1.8V which adds a little complication since the only S/PDIF transmitter chips I have on hand run on 3.3V.
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Offline actbluebe

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Re: Teardown: Amazon Echo Dot 2
« Reply #6 on: May 05, 2017, 06:52:41 pm »
Afaik I2S always uses 1.8V. I don't think an additional regulator would be a problem, but I am quite sure a 3.3V rail is somewhere in the device.
 

Online NiHaoMike

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Re: Teardown: Amazon Echo Dot 2
« Reply #7 on: May 06, 2017, 02:02:48 pm »
I2S usually runs at 3.3V, or at least that's what the DIT4192 I have on hand accepts. (It also accepts 5V logic levels, which is used in older equipment.)
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Offline actbluebe

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Re: Teardown: Amazon Echo Dot 2
« Reply #8 on: May 06, 2017, 04:48:56 pm »
Sorry, you are right! I think I am going to use a SN74AVC4T245 for the necessary level shift.
 


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