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Topic: i2c, wii nunchuck (Read 16673 times) previous topic - next topic

i2c, wii nunchuck

Hi,

with the now seeminly working i2c libary's, i thiought i would have a play. so i hooked up my wii nunchuck adaptor to the buspirate
see http://www.seeedstudio.com/depot/wiichu ... p-379.html

and tried to followthe commands in the code based at http://www.windmeadow.com/node/42?page=1

Long story short it didnt work. and being that im probably doing something silly i thought i would post what i did here to see what people think.

After some playing here is where i think its all going wrong.

firstly i set the buspirsate to i2c mode @ 5Khz, Power supplies on and pullups on.

then i run the macro (1) without the nunchuck connected.

Code: [Select]
4. I2C
5. SPI
6. JTAG
7. RAW2WIRE
8. RAW3WIRE
9. PC KEYBOARD
10. MIDI
11. LCD
12. HWI2C
(1) >4
MODE SET
Set speed:
 1. Slow(~5KHz)
 2. Fast(~50KHz)
(1) >1
I2C READY
I2C>W
POWER SUPPLIES ON
I2C>p
 1. Pullup off
 2. Pullup on
(1) >2
PULLUP RESISTORS ON
I2C>(1)
Searching 7bit I2C address space.
   Found devices at:
0x00 0x01 0x02 0x03 0x04 0x05 0x06 0x07 0x08 0x09 0x0A 0x0B 0x0C 0x0D 0x0E 0x0F
0x10 0x11 0x12 0x13 0x14 0x15 0x16 0x17 0x18 0x19 0x1A 0x1B 0x1C 0x1D 0x1E 0x1F
0x20 0x21 0x22 0x23 0x24 0x25 0x26 0x27 0x28 0x29 0x2A 0x2B 0x2C 0x2D 0x2E 0x2F
0x30 0x31 0x32 0x33 0x34 0x35 0x36 0x37 0x38 0x39 0x3A 0x3B 0x3C 0x3D 0x3E 0x3F
0x40 0x41 0x42 0x43 0x44 0x45 0x46 0x47 0x48 0x49 0x4A 0x4B 0x4C 0x4D 0x4E 0x4F
0x50 0x51 0x52 0x53 0x54 0x55 0x56 0x57 0x58 0x59 0x5A 0x5B 0x5C 0x5D 0x5E 0x5F
0x60 0x61 0x62 0x63 0x64 0x65 0x66 0x67 0x68 0x69 0x6A 0x6B 0x6C 0x6D 0x6E 0x6F
0x70 0x71 0x72 0x73 0x74 0x75 0x76 0x77 0x78 0x79 0x7A 0x7B 0x7C 0x7D 0x7E 0x7F
0x80 0x81 0x82 0x83 0x84 0x85 0x86 0x87 0x88 0x89 0x8A 0x8B 0x8C 0x8D 0x8E 0x8F
0x90 0x91 0x92 0x93 0x94 0x95 0x96 0x97 0x98 0x99 0x9A 0x9B 0x9C 0x9D 0x9E 0x9F
0xA0 0xA1 0xA2 0xA3 0xA4 0xA5 0xA6 0xA7 0xA8 0xA9 0xAA 0xAB 0xAC 0xAD 0xAE 0xAF
0xB0 0xB1 0xB2 0xB3 0xB4 0xB5 0xB6 0xB7 0xB8 0xB9 0xBA 0xBB 0xBC 0xBD 0xBE 0xBF
0xC0 0xC1 0xC2 0xC3 0xC4 0xC5 0xC6 0xC7 0xC8 0xC9 0xCA 0xCB 0xCC 0xCD 0xCE 0xCF
0xD0 0xD1 0xD2 0xD3 0xD4 0xD5 0xD6 0xD7 0xD8 0xD9 0xDA 0xDB 0xDC 0xDD 0xDE 0xDF
0xE0 0xE1 0xE2 0xE3 0xE4 0xE5 0xE6 0xE7 0xE8 0xE9 0xEA 0xEB 0xEC 0xED 0xEE 0xEF
0xF0 0xF1 0xF2 0xF3 0xF4 0xF5 0xF6 0xF7 0xF8 0xF9 0xFA 0xFB 0xFC 0xFD 0xFE 0xFF
I2C>

it seems that without a device attached the buspirate reads all addresses valid.
so i connect the nunchuck and i get

Code: [Select]
I2C>(1)
Searching 7bit I2C address space.
   Found devices at:
0xA4 0xA5
I2C>

seems that the address isnt what i expected it to be.

the code at the above website suggests that the address should be 0x52 but the bus pirate is finding 0xa4 and 0xa5

im guessing this is where im going wrong. anything i do to either address seems to give me no results.

does anyone have any idea's on what i should check? or where to go from here

Thanks

Peter

Re: i2c, wii nunchuck

Reply #1
There's no pull-up voltage on the pins if the Vpullup pin isn't connected to a power supply, so every address is always low during the ACK bit. Press V to get the voltage report and see the voltage on the Vpullup pin.

The Bus Pirate probes all raw I2C addresses, the address you have is the 7bit base address. 0x52 = 0b1010010, 0b10100100 = 0xa4 write, 0b10100101 = 0xa5 read. I'll try to find a good way to display both before the final release of v2.1.
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Re: i2c, wii nunchuck

Reply #2
Also, 50KHz is working fine for me.
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Re: i2c, wii nunchuck

Reply #3
Ok,

so i need to manually connect 2 pull up wires or doesnt it need em?

also i found http://svn.stuytech.com/public/nunchuk_read/ what confirms your addresses . maybe ill have to check it in the morning. its after midnight and im not thinking straight.

thanks for the quick reply.

Re: i2c, wii nunchuck

Reply #4
woot,

thanks ian,

Code: [Select]
VOLTAGE MONITOR: 5V: 4.8 | 3.3V: 3.3 | VPULLUP: 3.0 |
I2C>[0xa4 0x40 0x00]
I2C START CONDITION
WRITE: 0xA4 GOT ACK: YES
WRITE: 0x40 GOT ACK: YES
WRITE: 0x00 GOT ACK: YES
I2C STOP CONDITION
I2C>[0xa5 r:6]
I2C START CONDITION
WRITE: 0xA5 GOT ACK: YES
BULK READ 0x06 BYTES:
0xFF ACK 0xFF ACK 0xFF ACK 0xFF ACK 0xFF ACK 0xFF NACK
I2C STOP CONDITION
I2C>[0xa4 0x00]
I2C START CONDITION
WRITE: 0xA4 GOT ACK: YES
WRITE: 0x00 GOT ACK: YES
I2C STOP CONDITION
I2C>[0xa5 r:6
I2C START CONDITION
WRITE: 0xA5 GOT ACK: YES
BULK READ 0x06 BYTES:
0x78 ACK 0x7A ACK 0x2F ACK 0x7D ACK 0x6E ACK 0x17 *(N)ACK PENDING
I2C>

Re: i2c, wii nunchuck

Reply #5
ok,

looks like [0xa4 0x40 0x00][0xa4 0x00][0xa5 r:6] is the magic command.

i have the pullup pin connected to the data pin and running at 3.3v.

also it seems to loose its state if you leave it to long, hence the [0xa4 0x40 0x00]

if your quick you can just read with [0xa4 0x00][0xa5 r:6]

well that seems to be the case to me

Re: i2c, wii nunchuck

Reply #6
Here's my illustrated guide to the pull-up resistors on the Bus Pirate:
http://dangerousprototypes.com/2009/07/ ... resistors/

I don't understand your question about them. You need to connect the Vpu (Vpullup resistor) pin to the power supply of whatever you're interfacing. This will put that voltage through the pull-up resistors and onto the four bus pins (MISO, CLOCK, MOSI, CS), see also the mode guide:
http://dangerousprototypes.com/2009/08/ ... tax-guide/

The addresses are all the same. I2C uses the last bit to indicate read or write operations. The address you had before came without a R/W bit, the Bus Pirate shows it with the R/W bit.

Remember to end your final operation with a stop condition (]) to send the final NACK and end the read operation.

Quote
I2C>(1)
Searching 7bit I2C address space.
   Found devices at:
0xD0(0x68W) 0xD1(0x68R)
I2C>

Here's the new address scanner that shows the raw address and the read/write addresses.
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Re: i2c, wii nunchuck

Reply #7
yes i was thinking that i had to use the pullup pin to connect it to the signal i wanted to pull it up, not connect it to the power supply rail to pull them all up. my mistake.

im thinking that the pullups arnt needed anyway, i just disconnected them and it works fine still.

and my mistake with the address was i assumed the address was bits 6-0 not 7-1 with the r/w but being 0. it makes sense now.

this would make a nice easy tutorial btw. if you can get ahold of one of the breakout boards.

thanks again
Peter

Re: i2c, wii nunchuck

Reply #8
Edit: I see you got it before I posted :) Good work!

Quote
i have the pullup pin connected to the data pin and running at 3.3v.

There's your problem. Connect the pullup pin to the wii nunchuck's supply (the + pin). You could also connect it to the Bus Pirate's on-board supply if it matches the wii nunchuck (ie if the nunchuck runs at 3.3volts, connect Vpullup to the 3.3volt power supply).

Do you have the Bus Pirate external supply connected to the wii nunchuck power supply (+pin)? If the nunchuck is self-powered from batteries, it could be bad to connect the Bus Pirate's on-board power supplies to it at the same time (maybe it charges from USB, I don't know about it).

[s:]Bus Pirate --> nunchuck
MOSI/SDA-->D
CLOCK/SCL-->C
Vpullup-->+
GND--> - (GND)[/s:]
[s:]Let the nunchuck run from it's own supply, you don't need to enable the on-board power supplies (W) unless they're powering the nunchuck or the pullup resistors. Connect the Bus Pirate to the break-out board as shown above.[/s:]

You could connect the Bus Pirate's external supply to the + pin to power the nunchuck if there's no battery and you want to power it from the Bus Pirate's on-board voltage regulators. Assuming the nunchuck circuit supports power from that pin.

EDIT: I didn't understand how it worked, see my reply below.
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Re: i2c, wii nunchuck

Reply #9
I bet the nunchuck has pull-up resistors internally.

What does it run at? 3.3volts?
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Re: i2c, wii nunchuck

Reply #10
yes its a 3.3v device.

normally it would be powered from the wii remote so it has no internal power source.

i have just been looking on ebay. its about $15 aus to get a joystick + 2 buttons + a 3 way Accelerometer, with a simple i2c interface.

at that price you can offord to just cut the connector off and hard wire it.

pretty good damm value

Re: i2c, wii nunchuck

Reply #11
Ok, thank you. I misunderstood the breakout board and the nunchuck power supply.

Bus Pirate --> nunchuck breakout board
MOSI/SDA-->D
CLOCK/SCL-->C
Vpullup-->+ (looks optional)
+3.3volts-->+
GND--> - (GND)

This would be my recommended connection. It uses the Bus Pirate's on-board 3.3volt regulator to supply the wii nunckuck and the on-board pull-up resistors. The pull-up resistors might be optional because the nunchuck may have internal pull-ups. Setup for communications using the I2C library (m menu), enable the power supplies (W) and then the pull-up resistors (menu p, option 2).

Quote
[0xa4 0x40 0x00]

According to Scorpia and this Arduino code, setup the nunchuck at power-up with this command.

Quote
[0xa4 0x00] [0xa5 r:6]

Request and read new measurements with this command.

Awesome example, thanks for the contribution.
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Re: i2c, wii nunchuck

Reply #12
According to a comment here with no premalink:

Quote
I responded in the arduino forum, but wanted to add a bit here. You shouldn’t need pull-up resistors when playing with the Nunchuck. The Arduino has built-in pull-up resistors that work for small I2C networks.

Left by todbot on April 14th, 2008
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Re: i2c, wii nunchuck

Reply #13
just double checked this morning before i head off to work.

it seems that the pullup pin is not required. i get the same reading with or without it.

Using the pinout as described by ian i get consistant readings using the commands mentioned earlier.

the 6 bits are described here http://michael.lesauvage.name/cod4-nunchuk-leaner/

if you want an 8 bit reading for the accelerometer it looks to me like you can just read the 3,4,5 bytes. and not bother adding the extra 2 bits from the 6th byte to the reading.

Anyway im happy to see i can repeat what i found last night. it looks like a nice way to get a joystick for a project. its a pitty about the connector.

 

Re: i2c, wii nunchuck

Reply #14
Did some more quick tests.

I tried the hardware module on my A3 version chip. with the RC1 code. i got some weird stuff. but once i upgraded to RC2 then the i2c seemed to work fine.

perfect results at both 100Khz and 400Khz. i havnt tried 1Mhz yet. Looks like the RC2 upgrade helps this