Hooking up the 6 + 1 Mic Array to the MaiX BiT

The Risk-V chip on the MaiX BiT board also contains hardware FFT which should make it a respectable audio analysis board.  Sipeed offers a microphone array board with 7 mics and 12 RGB LEDs.

Unfortunately the mic array, which SeeedStudio  indicates is for Dock/Go/Bit, there is no real provisions made for the newer BiT board. Included with the mics is a 10 pin ribbon cable for the Go board, and an unadvertised (not on sales page inventory) 5x2 "dupont" connector cable which directly connects between the back of the mic array (not pictured on the sales page) and the Dock board area with mic connection labels silk screened on the board.

Some improvising is needed to hook up the BiT.  I offer 2 different solutions. The first that Seeed could help by throwing in a couple of replacement connector housings.

Connection Method #1
(You might have to start with a larger housing and cut it down to size)

The Seed OPL type for these is "Position Rectangular Housing Connector Receptacle Black 0.100" (2.54mm)"

Modified Cable Installed

 It's not too difficult to move the wires from one end of the provided 2x5 cable connector, to BiT suitable single row housings..

 Using a micro screwdriver or perhaps a needle,you can lift the little plastic tab tat locks the connector in the housing, pull the wire while gently lifting the tab (if your tossing out the old housing you can just break off the keys.)

 In my case I had to work with what I had on hand, here's a single pin Dupont connector (easy to give up, females are not as popular with prototype boards)  I freed up 4 housings and glued them together for pins 18-2 (I would not use superglue, the Cyanoacrylate, out-gasses and raises hell with electronic contacts.

Here's the modified connector which is suitable for a quick mic array demo (I used one row of the original housing, adding a single housing to make 6 on one side and 4 on the other side of the board..

Connection Method #2 

 Crafting a custom proto-board socket for the original 2x5 cable connector. If you are planning some more serious prototyping this might be the easiest way to go.  Most proto-boards have a 0.3" space between rows, in order to connect to the 2row connector I modified a dual male header pin connector with long pins, splaying the pins so they span the gap between rows.

Spanning the rows

A couple of pairs of needle nose pliers can help you do a cleaner job.  The pins are a bit brittle,(bend just enough.)   This is not the most stable connector, but it's passable, the connector tends up against the  USB or LCD connector at the ends of the board on a small 2 row proto board

The Connection Guide

I had to double check with Sipeed that the pin numbers used matches the Dock and Go board, which have nice clear mic and led connection pin labels.

Reference pin silkscreen
MAIX GO MIC array:

GND    -  -  -  -  -  -  -  -     Blk
VIN      -  -  -  -  -  -  -  -     Brn
MIC_BCK = IO18            Wht
MIC_WS = IO19               Red
MIC_DAT3 = IO20           Gry
MIC_DAT2 = IO21            Org
MIC_DAT1 = IO22           Vio
MIC_DAT0 = IO23            Yel
MIC_LED_DAT = IO24    Blu
MIC_LED_CLK = IO25    Grn

MaiX BiT Board Pins order

Org  Gry  Red  Wht
 21   20    19     18

22   23   24   25   Gnd   5V
Vio  Yel  Blu  Grn  Blk  Brn

2x5 Dupont cable connector 

Blk - GND       Brn - VIN 
Wht - 18        Red - 19
Gry - 20        Org - 21
Vio - 22        Yel - 23
Blu - 24        Grn - 25

I recommend you first connect the provided cable to the bottom of the mic array,with Black on GND, and double check that the color codes I recorded are still being used.

Here's a 13 line Micropython script that tracks a sound source direction with LEDs and heat map style blobs on the LCD.

from Maix import MIC_ARRAY as mic
import image
import lcd
while True:
    imga = mic.get_map()
    b = mic.get_dir(imga)
    a = mic.set_led(b,(0,0,255))
    imgb = imga.resize(160,160)
    imgc = imgb.to_rainbow(1)
    a = lcd.display(imgc)

---------------------------    For SeedStudio  ---------------------------

 Adding this photo of the back of the mic array, would reassure Dock buyers  that there is a connection for their board.

Sipeed 6 + 1 Microphone Array back

You probably want to add the 2x5 "Dupont" connector cable 0.100" (2.54mm) for Dock.  To the sales page Part List (the cable is included by Sipeed.)


Popular posts from this blog

Kendryte IoT AI processor summary

New High Performance (Risc-V) Processors Available to DIYers