AVR Freaks

My issue most of the time and will always be explaining. It's just something I'm no good at.

Few answers.

- I have studied the i2s bus to the point I'm sure its not my misunderstanding.

- The master is this wii-mote and it has devices you connect to it (slaves).

- my mega32u4 is going to act as one of the slaves. That is my plan.

- I have the Saleae logic , this is what I'm using to see the signal.

" The master sends the start sequence to acquire the bus. " This is what I'm not seeing. Both lines are high (2.7v) according to the analyzer. This is why I asked if that could be my problem. What I'm wondering is what it takes to get the master to start talking. It never pulls low, lines remain high.

"Level translation can be a challenge. " - Thus far I have read the same but many have no issues making i2c comm work with a wii-mote, although typical the atmega is the mast in my case its the slave.

Everything is managed by the master. You, as the operator, need to do what ever it takes to get the master to send a start condition. There is nothing the slave can do UNLESS there is some sort of back channel signaling system, such as an interrupt line, to request "service". 

 Yeah so that is the way I understood how it works. So there is nothing I can do here and yet nothing is happening. This system does not have additional lines, only SDL and SCA. As long as my pullups are there, I should see a start condition on the analyzer but I do not. I understand that I need to corresponds with the master here but if the master never begins the communication there is nothing to do.

"the wii-mote is not going to magically talk to slave devices", That would suggest the slave starts the communication, the opposite of what I was thinking.

I have attached what I see when the master and device talk. I was under the impression the master sends that setup write to 0x00. So I looped my code waiting, I would have expected to see the part I circled in yellow. I only see the two lines high.

Kartman, if my posts bother you so much why help? I'm not twisting anyone's arm here. Of course my question is vague, I come here when I do not understand things, not when I do.

Ok, so images then.

top is the real system, button is my attempt to emulate it. Once I enter my endless loop and based on what I think I know, I should see the master do something.

"My interpretation is you want to emulate a wiimote extension. Yes or no? " Yes.

" From my basic googling, the wiimote can be master and slave, but is usually the master " Yes but it's a slave to Bluetooth not i2c. My intention is to work with it in the master mode. 

 " Also what i’m not clear on is how the wiimote determines if there is an extension connected " So this is what I apparently am failing to to ask. This is what I have been try to ask and what I can not figure out. Now, perhaps my entire problem was that I took things for granted. I was nearly %100 sure this was normal i2c talk and the reason I figure it was not important to mention much about the wii-mote. For all I knew/know its just a normal i2c. So the question should be, how does a normal i2c master know when a attachment is there. Is there such rule? - guessing not.  Most gaming peripheral send a routine check. Like the Play station (isp), it sends out a 1 and waits for a reply. I was assuming this would be similar. More importantly and why I confused the hell out of you, is I figured this was a normal i2c question. Sorry, I clearly was wrong.....

Now that attached screen shot is the point at where I plugged in the real device to the wii-mote. I have no idea who initialed that command. My next go it it, I will see if I can initiate the command from the device end and see if it replies. I was pretty damn certain the master needs to first comm to all devices on the bus and the device must wait for a wake up. 

I may try the  Arduino  idea but I'm thinking ill get this without.

BTW: I found a project that does kind of what I want to do here. It is a bit more involved then what I want but I'm trying to study the concept here. If you have a moment to take a glance and can tell from his code what its doing, let me know. 

https://www.raphnet.net/electron...

his init does this

static void twi_slave_init(unsigned char addr)
{
    // initialize stuff
    twi_reg_addr = 0;

    // set slave address
    TWAR = addr << 1;
    
    // enable twi module, acks, and twi interrupt
    TWCR = _BV(TWIE) | _BV(TWEA);
}

followed by this

void wm_start(void)
{
    if (!wm_started) {
        // Start I2C
        TWCR |= _BV(TWEN);
        wm_started = 1;
    }
}

Does not look like he is sending anything there. Also take note this schematic has no pull-ups either. I'm still confused by that. Why does no example use pullups? The wii-mote does not have anything pulling up internally and I think relying on the MCU 20k is a bad idea.