19

For cold or dry solders on BGAs, you are working blind without X-ray or just functional testing like yours, so it's not easy for sure. First order of business would be to reflow the BGA with hot air. There are plenty of YouTube videos of GPUs being fixed this way in your home oven with some care. If this does not help and it's your one-off board and not ...


13

You need to use a transceiver when you want to bring out high speed signals from inside the FPGA and interface with the real world. Typical examples are to communicate with other high speed parts on the same board (for example another FPGA or ADC) or to interface off board (for example using PCI, HDMI or ethernet). In order to send these high speed ...


9

I have open source and open hardware sensor that would give you a working starting point: it is internet connected and transmits its temperature, humidity, and battery voltage every two minutes an will last for 3-5 years on 2xAA batteries. It is based on the M12 6LoWPAN module. I'll try my best to grab touch on all of your questions: Regarding band ...


9

The rule of thumb a lot of people use is that lower frequencies will have better "penetration" than higher frequencies. That's true in some cases, but not all. This is probably derived from calculating skin depth of materials. The skin depth is just how deeply into a material an electromagnetic wave of a particular frequency can penetrate. The equation used ...


7

This is an example of SMA plug and jack connectors: Most often, the plug type (left) is used on cables and the jack type (right) is used on instrument panels or pcbs. SMA connectors are: Small relative to connectors that preceded them, like BNC and N types. Suitable for use at frequencies up to 18 GHz. Widely used in industry for those frequencies. Quite ...


7

Unfortunately, BGA is not easy to rework. You could try reflowing again, or if you happen to have a via by the pin, shove a bit of flux there and heat with a hot air gun. If that doesn't work you have 1 of 2 options. You can either scrap the board and use a new one, or you can remove the IC, clean all of the pads, then you will have to re-ball the IC. This ...


6

Chipcon/TI CC110L (transceiver), CC113L/CC115L (transmitter/receiver). Flexible sub-1GHz radio. Claimed to cost $1 for pair of chips in volume. A cheap devkit is available.


6

Here is the outline of a link analysis: we'll assume you want a low bit-error-rate (BER), maybe 1 in a Billion; for normal OOK on-off-keying transmission, and similar for BPSK, etc, you'll need a signal-noise-ratio SNR of about 20dB with the noise measured in the data-bandwidth (or for some maths, in data-BW/2). Let's compute the room-temperature noise ...


5

You need to develop a Link Budget for your application. You know how much power the transmitter puts out, and you know how much power the receiver requires. You need to account for all of the losses and gains in between those two points. Most of the items are readily quantified, except for the free-space path loss, which is highly dependent on the distance, ...


5

SAE J1708 uses RS-485 transceivers, but connects the serial transmit data to the enable line of the driver rather than to the data line. This means that the driver is effectively switching directions on every bit. This is similar to CANbus, in which one of the bit values is "dominant" and the other is "recessive". The logic of each node is supposed monitor ...


5

Those types of transmitters and receivers only work on a single channel. The receivers usually employ a form of active gain control (AGC), so will increase the gain until something (usually noise) is received. The gain is reduced to an appropriate level when a transmission starts. Generally best practice is to: Agree on a bit rate between the two systems (...


5

Digi's Xbee modules may be interesting. The XBee PRO ZB has a maximum range of 3.2 km, and the modules have a completely transparent Zigbee protocol implementation. Means that you use the module as a simple UART connection. You want to control the pumps with this, so I'm thinking reliability! Pumps should not be switched off or on by others on the network,...


5

A standard piezoelectric ultrasonic transducer will not work efficiently at sub harmonics or harmonics - it's a 2nd order resonant mechanical device with high Q - there aren't different modes of operation as you might find with some crystals (for instance).


5

Basically what's done is some 8-bit message words have two corresponding 10-bit code words. One of these has positive disparity (more 1's than 0's) and the other has negative disparity (more 0's than 1's). When encoding you keep track of the running disparity. If the running disparity is positive and the next input octet gives you a choice of code words, ...


5

You don't tell us anything in your profile about your level of experience or education, so I'll give a very generic answer. The best tool to start with would be a spectrum analyzer, which can tell you what frequency the system operates on, and also allows you to learn something about the overall patterns of activity, and can offer clues about the modulation ...


5

In principle you should be able to multiplex MCU CAN signal lines, prior to their being used to interface to a CAN physical layer transceiver, using something like a 74HC4052. In practice, I'd suggest that it's not a very good idea to do so. The problem is that multiplexing would mean that you are guaranteed to periodically miss transmissions from each of ...


5

There are (in this context) two types of USB Micro-B connector; I tend to think of them as "long edge close to the PCB" and "long edge away from the PCB". You're using the "long edge close to the PCB" kind. Use the other kind and the order of the pins flips. Unfortunately there doesn't seem to be a search term (for Digikey or Element14, at least) that can ...


5

Did you estimate the proportion of time your system will actually be transmitting data? In most applications, this is very small, proabably less than 1%. Most of the time, transceivers are just idle. That is why it isn't really specified, because it doesn't account for much in the total power consumption. Also note that I saw it is actually specified for ...


5

You do not say where you are. The radio you reference requires you to hold an Amateur Radio operator's license. If you are in the United States, you need an Extra Class license (the highest), because the operating frequency is in the Extra Class sub-band of the 40 meter ham band. If you are somewhere else, check the local laws. (If you are in Thailand, ...


5

Would it be possible to take a standard SFP transceiver module and use that across free space rather than through a fibre? In other words, to point two transceivers at each other from a distance without any fiber optic cable between them. No. "Proof" to follow: The point of the fiber is to get almost all energy from the transmitter into the receiver. You'd ...


5

Those buffer the protected pin from the ESD event while ESD diodes do their job since it takes a finite amount of time for them to do so. It is similar to placing the ESD diodes as close to the connector as possible and as far away from protected pin as possible which uses the parasitic inductance of the traces instead of a resistor. Ferrite beads can also ...


4

Well, if you're going to have PSoC5's all around, I was recently reading about IEEE 1355. The DS-SE-02 signal link variant may do what you want. It calls for 4 signal lines: a data line and a strobe line in each direction. The only dedicated hardware I can find that implements 1355 is rad-hardened Spacewire gear, but this IEEE presentation claims that it can ...


4

Have you considered using RS485? There are already many components designed to work on RS485 buses.


4

A differential driver generates a differential signal with complementary (+,-) sides. A differential receiver receives a differential signal; that received signal is the difference between the + and - halves. For example, +0.25 - (-0.25V) = 0.5V differential signal. A differential driver can convert a single-ended signal to differential, but it can equally ...


4

The "standard" RC protocol is to transmit bursts of AM pulses[1], the relative positions of which are translated by the receiver into variable-width control pulses that get sent to the servos. It should be fairly straightforward for the smartphone app to send pulses out the headphone jack, which are then used to key a simple RF transmitter on a standard RC ...


4

It's a minature coax connector, used for connecting coaxial cable or antennas. This design is required for high-frequency single-ended signals. They're designed to have a characteristic impedance that is a reliable 50 ohms across a fairly wide range of frequencies.


4

8b/10b encoding has a wikipedia page with good explanations and also the encoding tables : http://en.wikipedia.org/wiki/8b/10b_encoding I think you can also look at some bus standards that use 8b/10b to have more practical examples.


4

I am answering this based on one particular SFP module's datasheet. I believe that everything I'll say applies in general, but I haven't checked it against the standard itself. I did find a copy of the standard online, but I'm not sure whether this version is current. TX_FAULT: "This signal is an open collector output (pull-up required on the host board). A ...


4

Yes, they are compatible. The functionality is determined by the chip, not by the surrounding components. With some care the NRF24L01 is also compatible with the NRF24L01+, RF70, and RF73. "It tells that it supports 1 to 6 communication? " - is that a question? - Yes, they all support 1:N communication (in datagram mode - no acknowledging/retransmission). ...


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