Hello,
I looked up nRF2401 chip and its a QFN format chip.
Since it doesn’t have pins, and its 5mm x 5mm, it doesn’t
come with a socket, and its 24 pins, how do I integrate such a small chip into my circuit to program it?
I looked for QFN sockets but I didn’t find any for this particular chip.
I didn’t buy the evaluation board since its expensive, and there must be some way of doing it yourself.
(I know its an inexperienced question, but I do need help with this)
Thanks
Ah, the horrors of surface mount technology. You can’t socket a chip that has several pins operating in the 2.5 GHz range.
The nRF chip does not have any flash or EEPROM onboard so you’ll have to send the configuration every time the power is cycled. Most of my stuff is done via microcontrollers, so configuration is just part of the uC bootup sequence for me.
If you’re just trying to test out this chipset with a preexisting design, would one of the mIRF boards work? $20 a unit is not bad for a small demo system, and it already has easy to adapt 0.1" breakout headers and the antenna and biasing circuitry already onboard.
I’m planning to connect it to a PIC microcontroller or the 6811 (but PIC might be easier because of the C compiler).
But I am getting closer to the solution that I need.
The problem is that what I’m building will be incased in a metal cylinder.
Therefore I have to design an antenna for the transeiver that I can mount on the outside of the casing.
This mIRF is good for the development stage of the communication.
But I’m wondering what I will do when I have to design and test the antenna. I need the leads so I can connect my own antenna to it.
This mIRF (on SparkFun) doesn’t give access to them because of the built in antenna.
I guess one of my solutions is to create a custom PCB just for the prototyping.
you can solder it. I would not try to work with these without making a PCB. I have just finished building a circuit board that has one of these on it. Although I have not tested it yet because I don’t have that test equipment quite yet.
just make the pads on your footprint hang out a little bit. The pins on the nrf2401 go up the side of the chip. when the solder connection is made, you will be able to see the solder run up the side of the chip.
If you do not have much experience soldering with SMT then it may be difficult. Here is how I do it: add a bit of flux on the board. then use some fine solder and add a little bit to each pad. make sure the pads have only a thin layer of solder. They should also have the same amount of solder. If some pads have extra, use some solderwick. Then add a little more flux. place the chip and heat a corner pin. That part is the hardest. It can be difficult to solder the first pin without bumping the chip. Once you get one pin, it is easy. check it and then do the opposite corner. You might need to add a tiny amount of solder if some pin won’t connect. use a magnifying glass to verify that solder runs up the side of every pin.
The flux and fine solder is important. On the board I just made, it is easy to see that every pin is connected. I left the center pad unsoldered because someone here said that it wasn’t required. If you are good, you could probably get that one soldered from underneath the board.
Yes, you’re definitely going to have to make your own board for testing in a metal cylinder. You might be able to use an SMA or RP-SMA connector onboard so you can hook up an antenna via coax or use a commonly available 3rd party 802.11b/g antennas (check the connectors). Either way, you may have issues determining if this will work out as your tube will probably act as a ground plane and shape the RF field in strange ways.
Just remember, you’re working with RF signals. Coax and PCB microstrip design is the name of the game if you hope to get anything decent from your PCB design.
The metal cylinder will be about 2 to 3 cm in radius with a shaft going through the center of it.
The thickness that I have to work with is about 3 to 4 mm. That’s why I need really thin components (such as the nRF2401).
I am having a problem visualizing how I’m going to solder this. The leads on the chip are much much smaller than the soldering iron. (even though the tip is pretty fine).
Thanks for the input everybody.
Also the antenna will have to be mounted on the outside of the cylinder. That’s why I have to built my own.
Any ideas on antenna design?