I’ve watched some tutorials and thought I’d have a dabble at creating my first PCB. Just to have a go really. My current perv board model works as is, but why not.
Well the project currently is a Pro Mini 3.3V 8MHz, a BME280 and a nrf24l01+ module. I originally was using the rf24 with the adapter module, which I’ve since removed and now have a capacitor across the voltage terminal of the rf24. All works great on 2 AA batteries.
My original plan was to create a pcb and solder everything directly. Have read about the rf24 and people having trouble, I thought I’d try the pcb with the rf24 antenna hanging over the edge. Another idea was to remove the ground plane, if that’d help?
Two AA batteries supply the voltage into ground. I’ve only just thought, should I put a capacitor at the input too?
My next idea, to make it more complicated was to get rid of the mini and go ‘barebones’ using ISP to program the 328p-au. I’d then need a voltage regulator, capacitors and resistors. Can anybody advice me on values needed? Or if its going to be too much of a faff to get sorted?
Thats a lot of questions. Just after some advice on feasibility and components.
Cheers
EDIT
I tried to add a photo of the prototype but it was rejected, even though the file was converted. It fits into an Altoid tin, with batteries.
I've built a few radio control hand-units using an Atmega 328 on stripboard and an nRF24 powered with a pair of AA alkaline cells and the battery life seems very good.
I have arranged for the nRF24 antenna to be clear of, and perpendicular to the stripboard. It is at the very top of this image
srnet:
About halfway through their life AA Alkalines will be down to 1.2V or so, is your circuit happy working at 2.4v ?
And with a 2.4v supply there is little headroom for a voltage regulator, apart from a boost converter type.
The current prototype has been working great on the two batteries but due to the low power consumption, the voltage has not dropped that low. But according to what I've read, the Pro Mini should shut down around that limit or maybe slightly more.
Are you referring to a voltage regulator for a bare bones type project though?
Robin2:
I've built a few radio control hand-units using an Atmega 328 on stripboard and an nRF24 powered with a pair of AA alkaline cells and the battery life seems very good.
I have arranged for the nRF24 antenna to be clear of, and perpendicular to the stripboard. It is at the very top of this image
I've seen that photo on another thread, looks great and does make me think the pcb idea may not be ideal. Although by not installing a ground plane, this may reduce the noise?
The RX module is a Keywish RF-Nano which works perfectly, although I'm not sure if that would transfer to a pcb easily enough, without problems. I'll leave that for another day.
I’ve done a little more reading into using the 328p-au and I came across this drawing. The bootloader would have to be installed by myself, which I could do whilst it’s on the pcb.
Anybody offer any advice to whether this would be all I need to get the chip working and then it’s a case of getting a clean voltage supply and connecting the nrf24 module. Would I need additional pull up resistors?
exiledyorkie:
The image didn't attach. It is now, see post #7
Pleas post an image as a JPG or PNG file rather than a PDF. Then you can make it visible in your Post and we don't have to download it. See this Simple Image Guide
Hi Robin. I did read your example, thank you. But I've tried before, from my phone. I've converted to a PNG but it still refuses to upload. Which leaves me the only option but to use the PDF, apologies.
exiledyorkie:
I've converted to a PNG but it still refuses to upload.
I suspect the problem is with EXIF data in the photo. If you can use a photo editor to convert it to a different format, from PNG to JPG or vice versa, it should get rid of the EXIF data.
I’m wondering whether to buy a tqfp32 to dip 28 adapter and test programming a chip first. Hopefully all I need, once the bootloader has been installed are the parts from the schematic.
EDIT:
I’m currently using a mobile. The options to display the picture are not an option, so unfortunately, it is there as a download again.
Thats not my schematic. As mentioned, I’m thinking of replacing the Pro Mini with a stand along chip.
Just curious to what other components I’d need to get the chip working with an rf24. I’m not sure if those components in the schematic are just to burn the bootloader or used in general running and then I can just connect the rf 24.
I think I need to order some stuff and experiment. I’ve found a cheap way to do this by buying a smd board to dip pcb. Just never soldered smd.