Spin Semiconductor

Are there any parts in-particular that needs to absolutely be closely positioned at chip itself ?

I'm considering a daughterboard arrangement for just the FV-1, for possible inclusion in multiple projects which may not be SMD.

You should put the crystal as close as possible to the chip. Also, it is very important that power bypass caps be directly next to power pins to ensure that the chip is stable during operation.

A daughter board sounds like a good idea. If I were you I'd place the bypass caps, input and output filters and DC blocking caps, etc. on the daughter board. And if you're using it in circuits where it's the only 3.3V circuit, maybe put a 3.3V regulator and even the EEPROM there too. Then it would really just be: power and control in, audio in/out. I'm sure with all surface mount devices you could make this board extremely small.

Good luck with your project!

I'm desinging a double side board for the FV-1 and have a question about the ground plane. Should be on the FV-1 layer or in the other layer?.

This it's going to be in a pedal enclosure, it is better to put the FV-1 in the "components layer" (as in a single sided board) or in the copper traces layer?.

It doesn't really matter, you can put the FV-1 on the component layer if that is easier for production. As long as the crystal and caps are right next to the pins it should be OK. A nice ground plane is a good idea, keep any noisy traces away from the audio traces, etc.

frank wrote:It doesn't really matter, you can put the FV-1 on the component layer if that is easier for production. As long as the crystal and caps are right next to the pins it should be OK. A nice ground plane is a good idea, keep any noisy traces away from the audio traces, etc.

Thanks a lot Frank, you always answer so quickly. I have another question, the Right and Left outputs are internally buffered?, can I short them together?

Uh, best on outputs to use a summing amp configuration rather than shorting together. Left and right inputs can be tied together and driven with the same signal but outputs as a general rule shouldn't be tied directly together.

I re-up this old thread for a few more questions about precautions to take for a commercial project based on the FV-1:
1) are there any recomendations regarding ESD and other interference matters?
2) are the inputs and outputs already buffered for line level signals or do they need external buffers or filters?

There are no special requirements on the interface, you just need to make sure the levels are OK and that they can drive the inputs properly.

Normally the in and out can handle line levels OK but I always prefer a buffer as you never really know what someone else did to their in and out drivers.

Thanks for your reply, Frank.

Do you have any suggestion for a good buffer design? Also, do I need a buffer for a guitar input as well?

For the line level buffer they can be as simple as non-inverting op-amp type, nothing special.

For guitar you really do need a buffer because a guitar's signal is so weak. See the schematics for the SKRM boards on the OCT site, the R01 or G01 versions. Not a fancy buffer but will work for guitar.

Could check the way I completed a Guitar effect unit that's capable for the DIYr. www.echotapper.nl look for eTap2hw

Frank, let's say I have a microcontroller sharing power lines and ground with FV-1, would you recommend some sort of power line isolation (e.g using ferrite beads) to keep the power fed to FV-1 immune to high frequency noise that might be present in the power line (due to microcontroller)? Or bypass caps next to FV-1 power pins are sufficient?

If you can lay it out so you use a star power and ground pattern that can solve lots of problems. Bypass caps are a must, if the micro has a PLL then keep it as far from the FV-1 as possible since it also has a PLL.

I've not had to use ferrite beads in any FV-1 design so far.

I'll try your suggestion, thanks