I've had good luck using the internal RC on most recent projects but did use ceramic resonators at one time. Thoughts on having PTH to mount one (ceramic resonator) instead of the crystal and caps? -----Original Message----- From: Olin Lathrop Sent: May 18, 2005 5:50 PM To: "Microcontroller discussion list - Public." Subject: [PIC] PIC prototype board comments? I may shortly regret ever asking this, but what the heck, here goes anyway. I'm looking for feedback on the design of a new product before it's too late to change. I'm seriously considering offering a family of PIC prototyping boards. I've never found the existing offerings to be that useful for just quickly wiring up and trying a PIC circuit, or for serving as the base for a one-off hand built device. They seem to be either aimed as showing off what a PIC can do, or try to solve too many problems with one board. The prototype areas I've seen are also too small and not very useful with just an array of unconnected holes. I've created a schematic of my idea what a PIC prototype board should be at http://www.embedinc.com/temp/qprot1.pdf. Here is a page by page overview: Page 1: Power supplies. The board will run from many cheap AC wall warts. There will be a 1.3mm socket for the same wall wart I use for the EasyProg and ProProg, plus screw posts for both AC and DC bare wire inputs. The final rectified voltage needs to be about 11-30 volts. DC supplies from 12 to 30V will work fine. A basic buck regulator makes 5.5V, which is linearly regulated to 5.0V with an LDO. I've done this in another design and it worked very well. Page 2: This is the PIC with its immediately surrounding circuitry. There are pads for two types of crystals, one thru hole and one surface mount. Of course at most one is intended to be used at a time. Pushbuttons to ground are connected to the port B interrupt on change pins with internal pullups. Page 3: RS-232 interface. The three jumpers make this optional. Page 4: Diagnostic LEDs. These are uncommitted so that you can wire them to any signal you wish. Each signal has two LEDs, one lit when the signal is high, the other when low. This is useful for seeing short pulses when a single LED would othewise be in the on state. It also avoids having to configure LED polarity. Page 5: Prototype area. There will be uncommitted strips of 5 pads surrounded by bus lines, much like the common "protoboards". The schematic is roughly laid out like the real board will be, except that there won't be a space every 10 pins. That's just for my sanity in working with the schematic. The pad strips and busses will be connected on the bottom layer, with the top being a ground plane flowing around the holes. The top silk screen will also indicate how the holes are connected. Overall I intend most of that pats in the schematic to be pre-installed, and therefore surface mount. Neither of the crystals would be installed, and there would be a DIP socket for the PIC. All the jumpers would be thru hole wires that come installed. They can be easily clipped to undo those sections of the circuit not used in a particular design. Yes I know that means in some cases people will be paying for parts they don't end up using. This makes sense when you realize that having only one variant to manufacture allows unit to be cheaper than the price of a few parts bought in volume. Instead of having two or three boards trying to cover lots of ground, I'd rather create more targeted boards that are good fits for what they are trying to to. I thought the generic PIC in a 28 pin DIP package would be the first target. 40 pins, dsPICs, CAN, USB, Ethernet, etc, etc, will all be different boards. I'm hoping to have the first one available by Masters. Comments? ***************************************************************** Embed Inc, embedded system specialists in Littleton Massachusetts (978) 742-9014, http://www.embedinc.com -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist