How about adding a dual opamp to assist analog conditioning.? Just something cheap & simple in the prototype area that can have resistors & caps easily added to it. RP On 5/19/05, Charles Craft wrote: > 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 > -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist