SMbus control on 280 GTX

[Hellshealer]

i have a few questions about this. in the data sheet for the 1165mf volteera chip the clock and data pins, it says they should be connected to the VDD.

on the GTX 280 they are both connected to the GPU output voltage. i have connected 2 wires to the data and clock legs and they are no shorts. but i still dont have controll via EVbot.



red dots show where i connected the wires too, blue dots are all connected. including the line on the top right hand side. blue is all connected to GPU voltage output.


so get controll of this chip via SMbus (evbot) do i have to disconnect it from VDD???

[RRainbo]

Why you just not use J11 connector? Its probably 3.3V,data,clock and gnd. and add pull ups to data and clock and unsolder resistor on pin R_sel0 and place instead it trimmer and try adresses from datasheet

That's the way i would tried it

[Hellshealer]

you post is extremely helpful, i don't know a lot about this stuff as i'm just starting to learn.

i have the data sheet for this chip and when i read it it confused me.

after reading back over the data sheet i think i have found the addresses and where to set them.

when you say add pull ups to data and clock what does that mean?

[RRainbo]

pull up is resistor that maintain logic High on bus,pin. It means resistor between Vdd(3.3V)and data or clock. With data i was thinking SD(=SDA=SMBus data)pin and clock is SC(=SCLK=SMBus clock) pin.
Dont know if pull up is neccesary maybe its already integrated in evbot or in card dont know.

[Hellshealer]

ok ill try the addressing first and see if it works, if not ill add the resistor(s)


4.7k ohms should be sufficient for pull up resistor right?

[TiN]

Pull-ups are necessary, it's open-drain lines, but they are already present on board, no need to add anything.

[Hellshealer]

ok thanks for that TiN thats awesome!

i have bad news tho, after i put the card back together i fumbled and almost dropped the card and tore off the wire i had for addressing and it tore off a solder pad that was on the pin side of the resistor. bit of a downer as it ripped out the entire pad but i have a friend on it who thinks she can put a trace wire back in and might be able to reconnect it or at lease have something connected to the pin.

ill keep this post updated.

[Hellshealer]

just a question. i have been reading the data sheet for 1165mf and for the addressing im assuming i need an address of 0 for the r/w on the chip. what is the gain setting? i notice that the higher the resistance the less the gain.

what gain does the EVbot need? when i did my original test it was getting a gain of 6 on address 0 @11.3k ohms. the evbot wouldn't talk to it.

[TiN]

That's VRM control stuff, gain have nothing to do with EVBot, just focus on address

[Hellshealer]

Table 5: Address Byte for VT1165M
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
1 1 1 0 addr[2] addr[1] addr[0] R/W

this is the table, im assuming bit 4-7 ar not addresses and that i need to choose from either 1 2 or 3 correct?

i cant test it atm due to not having any cards with a volteera chip set atm. my friend has both for repairs ><