1283 ticket datasheet

1283 ticket datasheet

[Marius Dräger]

http://www.winbond-usa.com/products/winbond_products/pdfs/PCIC/W86L785TS-S.pdf

some flaws i and somebody found out 
..
Don't worry about the different partnumber in the link, they made a
mistake in the document name. You'll see the correct partnumber in the
document itself. There are other mistakes too: 
Page 8 says "The 8-bit temperature data can be obtained by reading the
register." without telling you which one (it's CR27). 
In the tables on page 10,13 and 20 the values for R1 are wrong in the
row 85?C/30?C (should be 9.1K instead of 91K) and in the row 85?C/32?C
(should be 6.8K instead of 68K). Of course now that I understand the
purpose of those resistors I realize that they don't matter for a device
driver. 
Most important is the mistake on page 10 where the sentence reads: "When
monitoring CPUT1 (Pin 2) temperature exceeds temperature fault limit
(ex: 90 o C) in CR26, or CR27, pin6 TEMP_FAULT# will be asserted.". This
should really read: "When monitoring CPUT1 (Pin 2) temperature in CR27
exceeds the temperature fault limit in CR26 (ex: 90?C) pin6 TEMP_FAULT#
will be asserted.". 
On page 13 the document declares CR26 to be reserved, but I checked on
my board and it does indeed contain the temperature fault limit value. 

Another thing to note is that the 7-bit i?c address is 0101110. Normally
the lowest bit indicates reading from or writing to the chip. This would
make 0x5C the read and 0x5D the write address. However the chip is
clearly accessible at the address 0x2E on the A7N8X (same 7-bit address
just shifted to the right).
hope i can help
-- 
Marius Dr?ger <rentnerschreck@ecraft.org>

1283 ticket datasheet

[Mark D. Studebaker]

a very simple 1-sensor chip,
it would be straightforward to copy and modify the lm75 driver.
I'll update the new driver list and paste your info into the ticket.
thanks
mds

Marius Dr?ger wrote:
> http://www.winbond-usa.com/products/winbond_products/pdfs/PCIC/W86L785TS-S.pdf
> 
> some flaws i and somebody found out 
> ..
> Don't worry about the different partnumber in the link, they made a
> mistake in the document name. You'll see the correct partnumber in the
> document itself. There are other mistakes too: 
> Page 8 says "The 8-bit temperature data can be obtained by reading the
> register." without telling you which one (it's CR27). 
> In the tables on page 10,13 and 20 the values for R1 are wrong in the
> row 85?C/30?C (should be 9.1K instead of 91K) and in the row 85?C/32?C
> (should be 6.8K instead of 68K). Of course now that I understand the
> purpose of those resistors I realize that they don't matter for a device
> driver. 
> Most important is the mistake on page 10 where the sentence reads: "When
> monitoring CPUT1 (Pin 2) temperature exceeds temperature fault limit
> (ex: 90 o C) in CR26, or CR27, pin6 TEMP_FAULT# will be asserted.". This
> should really read: "When monitoring CPUT1 (Pin 2) temperature in CR27
> exceeds the temperature fault limit in CR26 (ex: 90?C) pin6 TEMP_FAULT#
> will be asserted.". 
> On page 13 the document declares CR26 to be reserved, but I checked on
> my board and it does indeed contain the temperature fault limit value. 
> 
> Another thing to note is that the 7-bit i?c address is 0101110. Normally
> the lowest bit indicates reading from or writing to the chip. This would
> make 0x5C the read and 0x5D the write address. However the chip is
> clearly accessible at the address 0x2E on the A7N8X (same 7-bit address
> just shifted to the right).
> hope i can help

1283 ticket datasheet

[Jean Delvare]

> I'm rather skeptical for this one. I would read the temperature fault
> limit from register 0x53, according to the data sheet. That said, the
> value in this register, from a dump one user provided, is 100, while I
> would expect 85 of 90.

About that point, I confirm my first guess. I saw a number of dumps of
that chipset, it turns out that register 0x53 always holds 0x55 or 0x64,
and is constant over subsequent dumps, while the value at 0x26 is not.
So my belief is that the register 0x53 holds the limit, but the data
sheet is wrong about the possible values, which are 85 and 100 degrees,
not 85 and 90.

I still don't know if it is possible to write to this register to change
the value.

-- 
Jean Delvare
http://www.ensicaen.ismra.fr/~delvare/

1283 ticket datasheet

[Jean Delvare]

Hi Marius,

I am in the process of writing a driver for the W83L785TS-S. I would
like you to answer a few question if possible:

> Don't worry about the different partnumber in the link, they made a
> mistake in the document name. You'll see the correct partnumber in the
> document itself.

Yes, noticed that.

> There are other mistakes too: 
> Page 8 says "The 8-bit temperature data can be obtained by reading the
> register." without telling you which one (it's CR27).

Agreed.

> In the tables on page 10,13 and 20 the values for R1 are wrong in the
> row 85?C/30?C (should be 9.1K instead of 91K) and in the row 85?C/32?C
> (should be 6.8K instead of 68K). Of course now that I understand the
> purpose of those resistors I realize that they don't matter for a
> device driver.

That's right, we don't care, but thanks for the clarification anyway.

> Most important is the mistake on page 10 where the sentence reads:
> "When monitoring CPUT1 (Pin 2) temperature exceeds temperature fault
> limit(ex: 90 o C) in CR26, or CR27, pin6 TEMP_FAULT# will be
> asserted.". This should really read: "When monitoring CPUT1 (Pin 2)
> temperature in CR27 exceeds the temperature fault limit in CR26 (ex:
> 90?C) pin6 TEMP_FAULT# will be asserted.". 
> On page 13 the document declares CR26 to be reserved, but I checked on
> my board and it does indeed contain the temperature fault limit value.

I'm rather skeptical for this one. I would read the temperature fault
limit from register 0x53, according to the data sheet. That said, the
value in this register, from a dump one user provided, is 100, while I
would expect 85 of 90.

I think that the confusion with register 0x26 in Winbond's sheet comes
from the fact that this register holds a second temperature value in the
W83L785R, and the 785TS looks like a cut down version of the 785R. But I
have value 89 in this register, so I admit it would be a reasonable
value for a limit as well, although that's neither 85 nor 90 either.

Could you provide a dump (using i2cdump) of your chip so that I would
have a second set of data?

For now my driver is read-only. I do not allow the user to write a
custom limit. There are two reasons for that:
1* I'm still not sure which register it is.
2* I'm not even sure it is possible to change this value. The datasheet
says the value is latched at startup, maybe that's not something we
can/should change after.

If you volunteer to make write tests, let me know and I'll tell you what
to do exactly.

> Another thing to note is that the 7-bit i?c address is 0101110.
> Normally the lowest bit indicates reading from or writing to the chip.
> This would make 0x5C the read and 0x5D the write address. However the
> chip is clearly accessible at the address 0x2E on the A7N8X (same
> 7-bit address just shifted to the right).

I don't see any problem here. I2C addresses are almost always given as 7
bit values. This is the real address of the chips. The fact that you
have to append a 0 or a 1 to write or read to/from the chip is another
thing. I've seen people using the "read address" instead of the 7-bit
address but that's confusing IMHO. So Winbond is right here :) We can't
blame them all the time.

-- 
Jean Delvare
http://www.ensicaen.ismra.fr/~delvare/