On 15 Apr 2012, at 21:12, David Forbes wrote:
>
> The DS2321 is not a real part, according to Google. The DS1307 is.
>
> It's true that you don't need a pullup on SCL, since it's only ever driven by
> the CPU. But the SDA line changes direction between writing the pot address
> and reading the
Bit old school I know, but if board _area_ is the issue, you could
mount the resistors vertically... Or (getting more outlandish) you
could mount them horizontally, but have them bridge over and sit on
top of the DS3231 package.
Jon
On Apr 15, 5:50 pm, Quixotic Nixotic wrote:
> I am driving a D
Just an idea, if you really don't have space for an extra resistor,
the port B has internal pull-ups that can be enabled and might do the
trick for you. You won't be able to use the I2C peripheral of the PIC
in that situation as it is on port C and cannot be re-located on the
18F2520, but with a bi
On 4/15/12 12:33 PM, Quixotic Nixotic wrote:
If only Farnell in the UK sold a resistor with wires that are 1/8w,
but I cannot find any.
I think they do - e.g. Farnell number 1700243 or 9343040 are 125mW 3k3
axial leaded - or are you looking for something else?
G
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On 4/15/12 12:33 PM, Quixotic Nixotic wrote:
On 15 Apr 2012, at 18:47, David Forbes wrote:
The generic ports are TTL, but when they get configured for I2C, they become
open-collector. I2C requires the pull-up resistors to implement its tricky
protocol over two wires.
You'll have to find the
>> The generic ports are TTL, but when they get configured for I2C, they become
>> open-collector. I2C requires the pull-up resistors to implement its tricky
>> protocol over two wires.
>>
> I am not using pins that can be configured as an I2C bus per se, but using
> two ordinary TTL level pins
On 15 Apr 2012, at 18:47, David Forbes wrote:
> The generic ports are TTL, but when they get configured for I2C, they become
> open-collector. I2C requires the pull-up resistors to implement its tricky
> protocol over two wires.
>
> You'll have to find the room for them. If it helps, 1/8 watt
On 4/15/12 10:37 AM, Quixotic Nixotic wrote:
The
DS2321 will be the only surface mount part...
I know. I was being silly.
The 18F2520 PIC ports I am using for the I2C bus say they are TTL, so
presumably they are not open collector, thus my question whether I need
any additional pullups.
T
People seem to find my Clock-It website and there's been a lot of interest
in my one and two tube clocks. I've got a reasonable set of fades and
display modes and I have also got a routine so the cathodes for each tube
can be swapped around by the user
People keep asking me if I can supply a ki
On 4/15/12 9:50 AM, Quixotic Nixotic wrote:
I am driving a DS3231 I2C clock from a PIC's pins. If the logic state of
the pins is always high or low, do I really need pullups on the bus? The
only reason I ask is that space is at a premium.
Ever taken apart a cell phone recently? Those 0201 resis
Yes, those pull-ups are necessary. The I2C interface pins on a
microcontroller (or on the slave device) are open-collector.
-Adam
On Sun, Apr 15, 2012 at 9:50 AM, Quixotic Nixotic
wrote:
> I am driving a DS3231 I2C clock from a PIC's pins. If the logic state of
> the pins is always high or low,
I am driving a DS3231 I2C clock from a PIC's pins. If the logic state of
the pins is always high or low, do I really need pullups on the bus? The
only reason I ask is that space is at a premium.
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Hi!
I'm looking for A-107 datasheets.
I have the data in a databook, but I'm looking for the datasheet which came
with the tubes as single papers.
Can anyone help?
Thanks
Dieter
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Sorry my last post to Nick DeSmith went to the group. It was meant to go
just to him. No big secrets or anything. I will just claim I was tired.
Tim Laing
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