What makes the perfect FLiP project board? Leave your ideas here please!
Ken Gracey
Posts: 7,392
Hey there,
Like many of you, I'm coming across projects where I'd like to dedicate the FLiP Multicore Microcontroller but I've never designed a PCB (it's been the ONE SINGLE goal at Parallax I have yet to achieve) so I'm usually plopping it on a breadboard or using some perf-board with point-to-point soldering. It's time that we make a single "FLiP Project Board". I'm looking for your ideas to make this board exactly what it needs to be for most of us. I'd like you to deposit your ideas here. To get this discussion going, I'm going to pose some basic ideas which are all mine, but you can comment on them.
FLiP Project Board Ideas
That list wasn't intended to steal the fun or identify the requirements for this project.
I've asked this same question before in another thread and I didn't follow through. I couldn't find that thread but somebody will locate it and post it here for x-ref. This time we will follow through and have this board ready by June since it's such a simple effort.
If you're interested, share your ideas and let's just get this one done!
Ken Gracey
Parallax Inc.
Like many of you, I'm coming across projects where I'd like to dedicate the FLiP Multicore Microcontroller but I've never designed a PCB (it's been the ONE SINGLE goal at Parallax I have yet to achieve) so I'm usually plopping it on a breadboard or using some perf-board with point-to-point soldering. It's time that we make a single "FLiP Project Board". I'm looking for your ideas to make this board exactly what it needs to be for most of us. I'd like you to deposit your ideas here. To get this discussion going, I'm going to pose some basic ideas which are all mine, but you can comment on them.
FLiP Project Board Ideas
3"x4" standard Parallax size
No manufacturing done at Parallax - PCB + all solderable parts provided in a bag
Less that $15-20 cost to customer - maybe even $10 - cheap enough to hand out now and then with a FLiP purchase (low-cost to allocate to a project, and use another instead of rework a current project)
No power supply or SMT parts
2.1 mm power jack location
Sockets for FLiP Module
4-6 3-pin header locations for servos or sensors
No manufacturing done at Parallax - PCB + all solderable parts provided in a bag
Less that $15-20 cost to customer - maybe even $10 - cheap enough to hand out now and then with a FLiP purchase (low-cost to allocate to a project, and use another instead of rework a current project)
No power supply or SMT parts
2.1 mm power jack location
Sockets for FLiP Module
4-6 3-pin header locations for servos or sensors
That list wasn't intended to steal the fun or identify the requirements for this project.
I've asked this same question before in another thread and I didn't follow through. I couldn't find that thread but somebody will locate it and post it here for x-ref. This time we will follow through and have this board ready by June since it's such a simple effort.
If you're interested, share your ideas and let's just get this one done!
Ken Gracey
Parallax Inc.
Comments
https://forums.parallax.com/discussion/167664/flip-breadboard-suggestion/p1
-Phil
-Phil
https://forums.parallax.com/discussion/168215/2-clock-kit/p1
You would need a high brightness LED model, in order to drive from MCU pins.
The 4 digit examples in the clock thread use shunt-drive which is simpler circuit wise, but a little more power wasteful.
As a plus, the three remaining ULN200x drivers could be used for something else.
-Phil
Correction to post above: With four resistors and without a current driver, you have to multiplex 1:32. That's why the display I did that way is so dim.
That's it! Nice find Jim (missed you last weekend, too!).
Ken Gracey
This one
https://lcsc.com/product-detail/Led-Segment-Display_0-56-Digitron-red-RED_C109200.html
claims 60mcd at 20mA, and is 40c/100 - could be worth trying ?
Maybe something to break out P28 and 29 from the FLiP, for I2C. I know any pins could technically be used for it, but I think the FLiP already has pullup resistors on these pins? (unless all of the I/O's were already going to be exposed - disregard then).
Location for a WX module socket (and wired up to the the FLiP such that it could be programmed wirelessly)
Socket to fit the WS2812 modules Parallax sells #28085
Sockets for a few other common I/O, like the PS/2 Mouse/Keyboard modules...although not sure if these are sold anymore, so maybe not. Some kind of buttons or joystick, like maybe the simple 5-position switch #27801
Socket(s) for whatever other I/O devices seem to be the best sellers
Hmm, I think all the 3 colour digital LEDs are surface mount, seems a shame to exclude them ?
Perhaps a 'no fine pitch SMT' is a better rule ?
QuickStart is (was) 2" x 3". Extend to 3" x 4" with room for a white plugboard, but have more prototyping holes in the area where the white plugboard would sit. The plugboard can be an add-on. There should be room for a 2.1mm power plug and a pair of holes at 0.1" for a two-pin polarized header as an alt power input. There could be dedicated servo or i2c or spi headers with positions for pullup resistors where required.
Bom: pcb, 2*sip header, 1*2row header, 74HC541 dip, 8 leds. sip resistor packs, 2.1mm socket, long header strip and optional pullup resistors.
@Ken, noticed the req list said no power supply parts, but that would be on my list for doing anything beyond straight logic. Yes, some op amp / analog can be done single supply, but sometimes +/- supply is just easier. Still want only one external source going to the project board. Easier, lower cost, and just less stuff in the box.
The three-pin servo-style headers are important -- the more the better -- with voltage selection shunts for every two positions.
I don't know where Parallax buys their connectors, but I've always found them to be the tail that wags the dog price-wise.
-Phil
I haven't paid much attention to later project Boards, I still use the old 5-pack serial version most of the time, I had some project in mind witch never realized, and bought some couple of those 5-packs.
What I really like is the processor in the center to build around it with very short wires. Besides not having build in USB. What I do not like is that ground strip placed somehow always in the way, not needed at all.
For me the PE-KIT is still the best way to start with a propeller, It shows that you just need a couple of parts to get a P1 running.
Since it should be for prototyping and one-offs, things like VGA sockets or PS2 sockets seem to be to restrictive to me, I have way more propeller then VGA monitors.
I would say 5V and 3.3V regulators, power jack, 2 power and 1 ground rail along one side, WX socket, FLIP socket, 4-6 3pin connectors with positions for jumpers to connect power and ground to the pins or not, to be able to use the header for different purposes.
I never liked the SMD LEDs, too small. Regular thru hole parts would be better for soldering disabled people like me.
Please do not waste any space for the quick-start buttons. IMHO they are just terrible and useless. You need to run a driver in a COG to use Buttons? Simply insane. Just throw some pushbuttons into the bag.
my two cents,
Mike
True enough, but we want good quality, so that the springs don't wear out too soon even with the range of wire sizes people are going to use. The worst thing for experimenting is when those contacts are flaky.
-Phil
Yeah, yeah, these are definitely OUT.
What I'd like to see on such a board:
* The few pads it would take to implement one or two Sigma-Delta ADCs.
* The few pads it would take to add resistors for a video DAC for composite video output.
* Pads for a first-order (cap and resistor) low-pass filter for PWM signal generation.
at least throw in some caps...
a PE style break out board, another nice idea.
But @Ken wants to build a board to plug in the FLIP module, a high volume ordered, quite affordable complete running P1 without need for much soldering at all.
Mike
1. I'm not optimistic that a sigma-delta ADC will work with the FLiP. The reason is the long lead lengths from the pins to the chip. Moreover, Ken said no SMD parts. Through-hole parts only add further inductance to an already lengthy feedback path.
2. Ken's budgetary parameters are quite restrictive. Even a $20 MSRP dictates no more than a $6.50 BOM for parts -- preferably $5 or less -- and that's the high end of his price range. He's hoping for an MSRP around half that. Don't forget that somebody has to order and kit the parts, and kitting is not a trivial exercise. The BOM will likely be dominated by the PCB, since 3.05" x 4" isn't exactly small, and there won't be any advantages to be had by panelization. As a consequence, I think we're looking at a pretty minimal carrier board design.
So what all can be crammed onto that board and still bring the total cost below $6.50 -- well below if possible? Remember, everything needs to be multiple-sourced, so an out-of-stock situation won't create an inventory issue. Aside from the PCB itself, we're talking strictly jelly-bean components here. That's the challenge.
-Phil
It's worth checking, as some form of ADC is a natural next step.
My guess is it would be 'good enough', but if performance is too poor, you could look at including a cheap MCU for ADC.
Your suggested 4 Digit LED fits inside that easily at ~ 40c
Footprints cost nothing to include, just the time to think about which ones to allow for, the point being not all parts allowed for, need to be always included.
eg a VGA HD15 is a modest footprint, in the compact versions, but not something you would drop into every bag - just give the part code.
Likewise a Character LCD footprint, reasonably standard, but a Char LCD is also not something you would drop into every bag.
I'd include SMD 3-4 Colour LED footprints too, as those demo well.
Other footprints :
Photo-interrupters are useful low cost sensors
https://lcsc.com/product-detail/Photo-Interrupter_ITR9606-F_C80816.html large, and sub 20c
or smaller
https://lcsc.com/product-detail/Photo-Interrupter_ITR9907_C135482.html
or common
https://lcsc.com/product-detail/Photo-Interrupter_ROHM_RPI-352_RPI-352_C79953.html
Tact Switch ? - always popular, these look to be sub 2c
https://lcsc.com/product-detail/Tactile-Switches_6x6x14-Plastic-head_C10890.html 1.6c/600
Thinking about it, if it did not deprive one of seeing just how little is required to make a prop work/useful, they could upgrade the Prop Ed kit with a flip instead of a bare prop. May even save a newcomer from frying their first and only prop chip.
-- https://www.allelectronics.com/item/mb-ps/breadboard-power-supply/1.html
There are a lot of interesting breadboard-friendly modules to play with, and these ensures plenty of power for the kinds of things I do.
The secondary supply input is limited to 9V maximum input though, and when the FLIP stands alone without external power, the USB_5V supply is not available. That is too bad, and I agree that an on-board 5V regulator that could run from 12V or more and could supply the regulated 5V power to both the FLIP and to the projects in standalone mode would be very useful, essential.
IMHO, pads or holes for other demos and devices (special ADC, video etc.) dedicated to certain pins can be included, but strictly as a user option. All pins should be available, with the usual exceptions for p28 to p31 as on the FLIP.
About the QuickStart touch pads. I agree they are flaky and a bad option for either a beginner or a pro. However some kind of switch input is needed for instant gratification with the LEDs. The kit could have locations for through-hole SPST switches to ground, with pull-up resistors, but to keep with the philosophy of not dedicating any pins, the switches/pull-ups would have to be isolated with diodes. Probably dirt cheap 1N4148s, since diode arrays tend to be pricey. The kit would not need to include all 8 switches.
-Phil
Outcome is cheapest DIP-ADC is $1.30+/3k, which is way above the cheapest MCU. (ouch)
The Prop SDM needs only manage 8~10 bit, to compete with the lowest end ADCs. Possibly a 74AHCU04 could boost the ADC specs a tad, with Vcc buffering, but those are 17c/3k and tagged non-stock in DIP or (~10c in SO14).
Digikey lists SMD MCUs with ADC's from 14c/3k, cheapest with +HW i2c is STM8, in SO8 29c/3k, Cheapest in DIP is 45c, or with DIP+HW i2c, 63c/3k (climbing, but still well under DIP-ADC)
- you'd probably want a MCU with a bootloader.
DIP MCUs from Asia are more common, but even there SMD is new designs. The new SO8 STC8H04A10 claims 0.7 yuan (~11c), or STC8H1K08S2A10 SO16 ~17c and those have a USB loader..
the 150mil SO packages are 1.27mm, which I think is not fine pitch smd, so can be soldered. A footprint with long pad fingers makes hand soldering even more forgiving.