Search found 44 matches

by Hagrid
Mon Apr 17, 2017 11:04 am
Forum: Getting started
Topic: Buffer Chips for Startkit GPIO
Replies: 1
Views: 4033

Re: Buffer Chips for Startkit GPIO

As I think you may have already found out, the pins are 3.3V and are at least 4mA - depending on which pin, it may be higher. From a buffering perspective, I tend to aim to limit the load on the host processor as much as possible. For buffering output pins, there are two points to consider. First is...
by Hagrid
Sun Mar 20, 2016 9:02 pm
Forum: XMOS Devices
Topic: Using TCXO as clock source
Replies: 6
Views: 9596

Re: Using TCXO as clock source

Thanks, mon2. It really does look like a copy/paste error in the XMOS documentation. The convincing arguments are: (1) the XUF doesn't have a 1.8V supply anywhere, (2) nor does it have a crystal oscillator that might use one as an alternative to the clock input, (3) the datasheet is silent on the su...
by Hagrid
Sun Mar 20, 2016 1:01 am
Forum: XMOS Devices
Topic: Using TCXO as clock source
Replies: 6
Views: 9596

Re: Using TCXO as clock source

Before I blow something up... My prototype PCBs should be on hand sometime this week, but perhaps they are wrong. For reference, the chip I am using is XUF208-256-TQ64. The issue of concern is the maximum voltage for the oscillator driving the chip. Another thread mentioned 1.8V in connection with a...
by Hagrid
Mon Feb 01, 2016 9:28 am
Forum: XMOS Devices
Topic: Using TCXO as clock source
Replies: 6
Views: 9596

Re: Using TCXO as clock source

Thanks.

There is a buffer needed it seems for the TCXO. Apparently other oscillators have it inbuilt but TCXO's don't because it produces heat which just adds to the stability problem.

Seems like a simple enough problem to solve - it is just bumping up the parts count.
by Hagrid
Fri Jan 29, 2016 2:04 am
Forum: XMOS Devices
Topic: Using TCXO as clock source
Replies: 6
Views: 9596

Using TCXO as clock source

I am looking at using a temperature compensated oscillator chip to drive an XUF208 to improve frequency stability for an instrumentation application. The output specs on the TCXO state: Clipped sine wave output voltage: 0.8Vp-p (http://www.farnell.com/datasheets/1701313.pdf) I can't see anything in ...
by Hagrid
Mon May 11, 2015 8:30 am
Forum: XMOS Devices
Topic: Power save mode?
Replies: 1
Views: 3681

Power save mode?

Could anyone outline what options are available to reduce power consumption? Sleep modes? Does a single active core use the same power as multiple active cores?
by Hagrid
Mon May 11, 2015 8:24 am
Forum: Development Tools and Programming
Topic: timer overflow
Replies: 11
Views: 8603

Re: timer overflow

Why do you need to capture the timestamp into time? Opens the door for creepage.

case t when timerafter(time):
time += 1E6;
by Hagrid
Sat May 09, 2015 5:17 am
Forum: Getting started
Topic: i2c signalling?
Replies: 20
Views: 27822

Re: i2c signalling?

Ooh nice. Anything else new wrt ports? A usable cross-thread PEEK, O/D on multibit ports, anything else? It's not just related to ports, but on xCORE 200 you can now divide down an external clock (1b port input to clock block), rather than having to do the buffered port clock stream trick.. Does th...
by Hagrid
Wed Apr 29, 2015 10:39 am
Forum: Getting started
Topic: i2c signalling?
Replies: 20
Views: 27822

Re: i2c signalling?

Doing i2c from a single multipin port would be problematic. As the state of the pin is controlled by the direction (logic high is input state, logic low is output low state) you would be unable to have different states on different pins on the same port as all pins on the port have to be the same di...
by Hagrid
Tue Apr 28, 2015 2:59 am
Forum: Projects
Topic: xSYS connection best practice
Replies: 0
Views: 10054

xSYS connection best practice

Implementing a full xSYS connection, what are the recommended best practices?

1. Series resistors with some or all signals? Which ones? What values?

2. Signal path length matching. Is this required or desirable? Which signals? What tolerance?

3. Other recommendations...