# Tag Info

1

LVDS as a physical layer will do multidrop into the Gbps. You might need to roll your own higher comms layers, but iirc Xilinx can supply IP to at least layer 2 go with the LVDS transceivers in their FPGA's. They also offer GTP transceivers in their higher-end FPGA's but I'm not sure whether GTP supports multidrop. Also, there are many standalone LVDS ...

1

All a DCM can do is add jitter - it's a tapped delay line, so the output clock can jitter as the taps change. And for the same reason it can't remove any jitter that is already there. If you want to "clean up" the clock signal, you need to use a PLL - check the datasheet to see if the FPGA PLLs can cope with the spread-spectrum PCIe clock. Or use a ...

0

A few observations. 1) will your uno be placed so that it can reach all the sensors via bluetooth? 2) why not just add bluetooth to your central server and avoid the time synch wakeup altogether, since the central server will be on all the time. 3) dead reckoning using the timer will eventually drift. You will want them to have your peer to peer network ...

0

You can take a look at http://www.keil.com/dd/chip/3648.htm LPC 2129 ARM7TDMI-S with CAN support. This can help if you fix your interface as CAN. You can also have Industrial or MIL grade connectors and cables because of your temperature constraint. Check out vendors like Radiant cables, TE connectivity, Amphenol, Allied Connectors which manufacture stuff ...

1

Having run longer HDMI runs myself, my guess is that the problem is not voltage drop, but rather signal skew. The current in a HDMI cable is low, and the resistance is low, so voltage drop should be in the millivolts at most. Your cable acts as a filter with non-zero frequency dependent attenuation and non-zero phase skew. You need to add a counter-filter ...

1

You don't want to send a single packet for every sample. That's because the packet has headers as well, and that means inefficiency in the transfer. Putting several samples into a single packet will both increate the efficiency and get you over your minimum packet size. The upper limit on the number of samples is the maximum latency that you can tolerate. ...

0

It may not be 100% what this question is asking, but for projects where the production runs are fairly small I've started to see people embedding pre-built boards like the raspberry pi. This has a lot of advantages: The price isn't too much more than one of the higher end CPUs with ethernet (at least for low-volumes), and you skip a whole load of ...

3

You might be interested by these Application Notes about transformerless/magnetic-less ethernet application Intel AP-438 : http://www.intel.com/content/dam/doc/application-note/8255x-fast-ethernet-controllers-without-magnetics-appl-note.pdf TI AN-1519 : http://www.ti.com/lit/an/snla088a/snla088a.pdf They both have an example of transformerless operation ...

4

What you really need is a different variety of PHY, so called "backplane phy". Those are specifically designed to work with capacitive coupling over PCB traces. The relevant standard is called 802.3ap. Here's a nice overview: ftp://ftp.t10.org/t10/document.05/05-214r1.pdf Many modern PHYs can be put into a 1000Base-KX mode through a bit of configuration ...

1

Etherent uses various types of line codes to ensure that the transmitted data is DC balanced. 4b/5b is the line code used in 100 Mbit ethernet, and then it is transmitted with MLT-3 encoding. The 4b/5b code caps the number of ones and zeros you can get in a row. Then MLT-3 transmits three different voltage levels, -1, 0, and +1. A transition represents a ...

2

The transformers are there to help impedance match to an RJ45 Ethernet line so if you're confident that the impedance match you will be fine even for tens of feet. Small print Transformers also protect silicon from line disturbances that might otherwise kill silicon so be aware of this. They also isolate galvanically the two systems and stop earth loops ...

1

Here's a clue: - It's all about matching impedances to avoid data corruptions due to incorrectly terminated cables. Take a look at the table circled in red. With a turns ratio of $\sqrt2$ impedances are transformed by this squared. So an impedance of 24.3 ohms for Rt becomes transformed to 48.6 ohms. As the CS8900A outputs differentially the impedance ...

1

The turns ratio is based on the design of the transceivers in your PHY. The ethernet specification calls for a +/-2.5V signal level over the twisted pair, so if your transceiver outputs e.g. 3.5Vpp, this needs to be 'transformed up' to 5Vpp with a 1:1.414 turns ratio transformer. If you don't adhere to this, your device may not operate together with other ...

Top 50 recent answers are included