Hey guys,I'm an undergrad student from BITS Pilani,Goa campus,heading the on-campus CUA Initiatives.We're trying to build a custom PSoC3 board,to better suit our specific needs and for wider exposure of this tech amongst our student body.
The first version is going to be a bare-bones solution,i.e just the PSoC3 chip,the required capacitors around and a programming header,with as many pins broken out to headers as possible.All power rails will be provided via off-board supplies,or not.Lets see.
A few specs the board needs to meet,( I do understand these might be impossible to meet
2.Can be etched using toner-transfer method of self PCB Fabrication.(Hence the first point)
3.Can be hand soldered
All these point toward the DIY nature of board production and assembly,essential for easy access to PSoC3 solutions,without requiring large numbers of FTKs and DVKs.
Let me discuss each part of that in some more detail,since I want some help on this design.
The PSoC 3 Chip - Owing to the fabrication constraints mentioned above,we're going to go with the 48pin SSOP chips of the PSoC3 family for our initial designs. We would like to go with the CY8C3866PVI-021 (most feature rich SSOP part) but its $14.So,our next option is the CY8C3246PVI-147,which is priced at $7.We do lose a few features,but lets see how that goes.
Just the required capacitors - We'll probably have 0805 SMD caps where needed,according to the schematics(I'll come to that) in the datasheet for the PSoC3 Family.
Programming Header - Now this is the tricky bit.We would like to reduce cost and parts,hence the mini prog would be the first to go.That leaves us with 2 options,one - build that FX2LP programming circuitry OR,do a one-time program of a custom UART/SPI bootloader. The latter is more attractive,since it goes along nicely with our aims on this board(Simple to build,Cheap and widely useable).I have been following some topics here on the forum in this regard,and hope that this can be implemented.We do have old miniprogs from our PSoC1 kits,Could those be used to burn on the bootloader? ..Or is the new MiniProg3 absolutely necessary for that?
Power - There are lot many power rails than conventional controllers,so each of these will be broken out to a header(on our first fab).Adding some LDO voltage regulators etc will be a plan for the future,since as of now,the aim is to get a basic programmable platform.
Schematics - I'm not too sure on how the older MiniProgs(I2C ones..) can be used to program the psoc3,so I'm a little hazy on those details.If someone could clarify the chip's basic requirements with respect to programming etc for this initiative,I'd be greatful.
Comments,suggestions and criticism are most welcome on this.