wanted: robotics multi-IO shield, 8 motors, lot of IOs

[davenull]

I'm looking for a robotics multi-IO shield providing plugs for external L298 H bridges (or even more powerful ones which I already have, on proprietary backpanes)
- to control 8 motors feat. rotary encoders
- plus extra digital (at least extra 16x) and analog pins (ADC 10-bit, at least 10x)
- plus at least one extra free i2c and UART for external devices (GPS, IMU, ...)

It's for an autonomous robot with 1 6DOF arm, all motors PID-controlled, 2 motors for odometry, so quick pin reading is required (all pins in polling cycles of about 100µs).
I am programming in C/C++ (g++, Raspbian Jessie, Geany IDE), no Python.

Is there such a thing available? Perhaps even hooking up several different shields or backpanes?


(p.s.,
I already tried hooking up 1 Arduino Mega or Arduino Due to 1 Raspi, but that'ts a very complicated thing to do for setting up a real-time communication between both boards, both by UART and by i2c, or by SPI - nevertheless, the Arduino part is not so hard to do for me to do as I've got already a little basic experience in programming Arduinos. And actually when finally being interfaced by highspeed, a Due or Mega would fit by it's pins perfectly - or something similar...)

[mikronauts]

Hi,

I'm looking for a robotics multi-IO shield providing plugs for external L298 H bridges (or even more powerful ones which I already have, on proprietary backpanes)
- to control 8 motors feat. rotary encoders
- plus extra digital (at least extra 16x) and analog pins (ADC 10-bit, at least 10x)
- plus at least one extra free i2c and UART for external devices (GPS, IMU, ...)

1) 8 motors require 16 to 24 digital I/O's (DIRA/DIRB or EN/DIRA/DIRB, I recommend the latter)
2) 16 extra digital I/O and 10x 10 bit ADC inputs
3) 1 extra I2C, 1 extra UART

You can do it with RoboPi, and a PiDroidAlpha, which would give you:

RoboPi: http://www.mikronauts.com/raspberry-pi/robopi/

(see link above for RoboPi Build Manual and RoboPi User Manual)

8x 12 bit ADC (5V)
24x FlexIO (each I/O can be servo, pwm, digital in, digital out, ultrasonic distance sensor, 5V safe))

PiDroidAlpha: http://www.mikronauts.com/raspberry-pi/pi-droid-alpha/

(see link above for PiDroidAlpha Build Manual and PiDroidAlpha User Manual)

8x 10 bit ADC 5V (you could order it with 12 bit ADC instead)
8x Pi I/O with voltage dividers (5V safe) (can be servo, pwm, digital in, digital out)
16x additional (5V) I/O

This gives you a total of 16 analog inputs and 48 digital I/O, with an 8 core 32 bit RISC co-processor (on RoboPi)

- 16x ADC inputs
- 24x FlexIO (each I/O can be servo, pwm, digital in, digital out, ultrasonic distance sensor, 5V safe))
- 8x Pi I/O with voltage dividers (5V safe) (can be servo, pwm, digital in, digital out)
- 16x additional (5V) I/O

More than you asked for

For this configuration:

- do not populate the L293D section on PiDroidAlpha (it uses 2 Pi I/O's and four of the other I/O's)
- Stack PiDroidAlpha on the Pi
- connect RoboPi to PiDroidAlpha with 4 pin hcom cable and 1 wire for logic 5V

This would give you:

Configuration:

- use EN/DIRA/DIRB style motor drivers
- use 8x Pi FlexIO for the PWM signals to the motors
- use 16x Pi FlexIO for quadrature input (you would have to extend the firmware for quadrature input)
- or use the 16x digital I/O on PiDroidAlpha and read the quadrature inputs over SPI (may work, depends on pulses/sec)
- you would have the Pi's I2C port available for additional I2C peripherals
- you could extend the RoboPi firmware to provide additional serial ports

If you need even more I/O, you could add up to 4x PiRtcDio boards, each of which provides 32x 3v3 digital I/O, and one could have its RTC section populated.

PiRtcDio: http://www.mikronauts.com/raspberry-pi/

All of the above products are in stock, and can be ordered direct from me, from my Tindie store, or Ebay.

It's for an autonomous robot with 1 6DOF arm, all motors PID-controlled, 2 motors for odometry, so quick pin reading is required (all pins in polling cycles of about 100µs).
I am programming in C/C++ (g++, Raspbian Jessie, Geany IDE), no Python.

Is there such a thing available? Perhaps even hooking up several different shields or backpanes?

Yes, see above.

I designed RoboPi specifically for advanced robotics (and DAQ applications), and I make sure my products inter-operate - thus you can have a RoboPi, a PiDroidAlpha and four PiRtcDio's attached to one Pi

I even have my own support forums for my products

I have a C/C++ API for RoboPi

for C/C++ programming of PiDroidAlpha and PiRtcDio you need to use standard pigpio or WiringPi libraries.

(p.s.,
I already tried hooking up 1 Arduino Mega or Arduino Due to 1 Raspi, but that'ts a very complicated thing to do for setting up a real-time communication between both boards, both by UART and by i2c, or by SPI - nevertheless, the Arduino part is not so hard to do for me to do as I've got already a little basic experience in programming Arduinos. And actually when finally being interfaced by highspeed, a Due or Mega would fit by it's pins perfectly - or something similar...)

[davenull]

that looks and sounds amazing, just the shipping fees and the customs, plus the VAT...

do you have a distributor in Germany or Europe/EU (common market) ?

if you don't have one: would you wish to choose e.g., Watterott?
(no, I don't get commission... )
http://www.watterott.com/index.php?page=index

(Watterott is also building and distributing Genuinos for middle and northern Europe, the company is reliable and inexpensive)

[mikronauts]

Thank you

I designed my boards to have the features I'd want, figuring other users would want similar features.

Unfortunately I don't have a EU/UK/German distributor yet, but I would definitely like some!

I do have a US distributor for PiDroidAlpha (Ameridroid.com) but they don't carry the other products yet.

I can't do anything about duty, taxes and VAT unfortunately.

At the risk of sounding self-serving, the cost of shipping per board becomes quite affordable on larger shipments.

I can ship 1kg via DHL to EU for $50USD, that is enough for about eight of my larger products (RoboPi, PiDroid etc)

So if you have some friend and can arrange a group buy, the shipping is reasonable.

Or if you can encourage some EU/UK/German distributors to carry my products..

that looks and sounds amazing, just the shipping fees and the customs, plus the VAT...

do you have a distributor in Germany or Europe/EU (common market) ?

if you don't have one: would you wish to choose e.g., Watterott?
(no, I don't get commission... )
http://www.watterott.com/index.php?page=index

(Watterott is also building and distributing Genuinos for middle and northern Europe)

[davenull]

below EUR 20 (including shipping) it's free of customs and VAT,
below (IIRC) ~EUR 120 (including shipping) it's free of customs but plus 19% VAT,
higher than ~EUR 120 (including shipping) it's plus 20% customs plus 19% VAT,

so the cheaper, the cheaper, in this case

ps,
but maybe you'd wish to contact Watterott by yourself?

[davenull]

pps,
forgot to mention:
As I don't solder, I needed everything completely assembled.

and ppps,
wouldn't be the RoboPi better then?

[mikronauts]

I can't do anything about VAT, customs or DHL rates. I definitely cannot sell for <20EU.

I do have a cheaper shipping option, but you won't like it as it is uninsured and with poor tracking - which means if it was lost, I could not give you a refund, and it takes 3-4 weeks to get there for $32USD. NOT RECOMMENDED.

I can't contact the distributor, as when I have done that in the past, they ask for 40%-50% discount, which I cannot give them.

If you like, we can take the shipping / order discussion to email... mikronauts at gmail dot com

below EUR 20 (including shipping) it's free of customs and VAT,
below (IIRC) ~EUR 120 (including shipping) it's free of customs but plus 19% VAT,
higher than ~EUR 120 (including shipping) it's plus 20% customs plus 19% VAT,

so the cheaper, the cheaper, in this case

ps,
but maybe you'd wish to contact Watterott by yourself?

[mikronauts]

I can have the kits assembled, but the price is significantly higher (techs here charge $25/hr)

I suggested 1x RoboPi + 1x PiDroidAlpha to keep your costs down, however there is a way to use 2x RoboPi's instead.

pps,
forgot to mention:
As I don't solder, I needed everything completely assembled.

and ppps,
wouldn't be the RoboPi better then?

[mikronauts]

FYI, shipping from Canada to EU etc sucks, and is costing me a lot of sales.

Canada Post used to have a $20 tracked / insured to $100 service, but it is now $60

DHL is the cheapest for $50

For inexpensive shipments, I can use a freight forwarder who will mail them from the US, but the tracking is very poor (basically package shipped / package dropped of for recipient (second one is often mising)) with only $50 insurance.

I've talked to a few distributors in EU/UK, but talks fell apart due to the terms they wanted: (one or more of the points below)

- 40%-50% margin for them
- low MOQ for them ordering
- selling on consignment
- me drop shipping for them

Given the cost of parts for RoboPi etc., I can't get anywhere near those kinds of discounts, and I can't raise my prices to give them more margin.

Drop shipping is out of the question due to high shipping costs from Canada.

[davenull]

ok, I would choose then 1st of all just 1 RoboPi, assembled.
For motor H bridges, I'm always using 3 pin L293/L298 comaptible ones, plus 2 encoder pins.

As I'm a complete newbee to Raspberry ( just started with it 3 weeks ago): can you show me example source code for Raspbian g++:
- which extra lib includes (Geany settings)?
- reading RoboPi digital pins
- reading RoboPi analog pins
- reading RoboPi rotary encoders


(I just use these codes so far:
for digital + analog GPIOs: wiringPi,
for rotary encoders this wiringPi example: viewtopic.php?f=33&t=123628&p=836058#p835913)

[mikronauts]

ok, I would choose then 1st of all just 1 RoboPi, assembled.
For motor H bridges, I'm always using 3 pin L293/L298 comaptible ones, plus 2 encoder pins.

I use those L298N's a lot myself

You would need 5 pins per motor (EN/DIRA/DIRB/ENCA/ENCB), so one RoboPi does not have enough I/O (40) for eight motors, however you could add a MCP23S17 or MCP23017 for the 16 direction bits.

As I'm a complete newbee to Raspberry ( just started with it 3 weeks ago): can you show me example source code for Raspbian g++:
- which extra lib includes (Geany settings)?
- reading RoboPi digital pins
- reading RoboPi analog pins
- reading RoboPi rotary encoders

Please see the RoboPi User Manual (download from http://www.mikronauts.com/raspberry-pi/robopi/) sample code.

The library does not currently support rotary encoders, however the API is extensible, and I have been meaning to add encoder support for the Dagu Rover 5's high resolution encoders.

Can you send me a link to the encoders you are using so I can see if they are compatible?

(I just use these codes so far:
for digital + analog GPIOs: wiringPi,
for rotary encoders this wiringPi example: viewtopic.php?f=33&t=123628&p=836058#p835913)

Thanks for the encoder example, I will check it out.

FYI, you could keep using the same rotary encoder code if you connect the encoders to the Pi's I/O, RoboPi only uses TX, RX and GPIO#17

Here' is the part that will make you run away... I charge $99.95USD for an assembled and tested RoboPi, plus $50 for DHL shipping.

(It takes an average of 1.5 hours per RoboPi when I get them assembled and tested, and my tech charges me $25/hr.)

[mikronauts]

I took a look at your encoder link, it is similar to the code I've used before with the Rover 5, I suspect it would work for the Rover 5 as well.

I can add encoder support easily to the firmware and the C/C++ library, however the Python API would not be updated for a while.

Note: I can only test the encoder code with my Rover 5's.

[mikronauts]

FYI, acording to http://www.dutycalculator.com/new-impor ... 196222029/

there is no duty on "Electronics Prototype / Control or Adapter Unit" on a $200USD+$50USD s/h shipment to germany, just VAT

[davenull]

ah, ok, I just knew tis one, roughly:
Duty is not charged if:
the FOB value, i.e. the value of the goods excluding shipping and insurance cost, does not exceed €150

VAT is not charged if:
the FOB value, i.e. the value of the goods excluding shipping and insurance cost, does not exceed €22

[davenull]

I don't have the Rover of either release and so don't know how quick it's encoder values may change,
the encoders I am using are rotating by up to 1-2°/ms, == 2-4 encoder ticks/ms.
FYI, I'm using most of all Lego Mindstorms encoder motors (EV3 medium/large, and NXT).
http://www.mindstormsforum.de/viewtopic ... 309#p65086

your manual is fine, the commands look like Arduino Sketch code - is your lib compatible to wiringPi, too, if additionally included?
(Finally the Raspi B+ has 12 GPIOs which could be used for the robot additionally to the RoboPi's ones.)

[mikronauts]

I don't have the Rover of either release and so don't know how quick it's encoder values may change,
the encoders I am using are rotating by up to 1-2°/ms, == 2-4 encoder ticks/ms.
FYI, I'm using most of all Lego Mindstorms encoder motors (EV3 medium/large, and NXT).
http://www.mindstormsforum.de/viewtopic ... 309#p65086

Looks like a nice motor! But it seems to be I2C based without encoder pulse outputs.

Rover 5 as I recall gives 333 pulses per revolution, so is probably maxed out around 1k pulses per sec at a guess.

Right now the code I used was set up for just two encoders, so I'd have to add support for more.

Do you really need eight encoders? For my bots I've been fine with two so far.

As the code is in assembly language, I don't think it would have issues with once change every 250us, even with 8 encoders that's just over 30us available per encoder. Worst case I'd have to use two of the eight cores for encoders... I think my code can support 12 encoders, using up all of RoboPi's digital I/O.

Good thing I already have 2 encoder code that should be easy to expand to more

your manual is fine, the commands look like Arduino Sketch code - is your lib compatible to wiringPi, too, if additionally included?
(Finally the Raspi B+ has 12 GPIOs which could be used for the robot additionally to the RoboPi's ones.)

The RoboPi API (like WiringPi and Arduino sketches) is similar to Wiring.

Right now, I don't believe that RoboPiLib and WiringPi could be linked in the same executable.

RoboPiLib should co-exist nicely with joanne's excellent pigpio http://abyz.co.uk/rpi/pigpio/cif.html

[davenull]

no,no, the Lego motors are a simple DC motors with simple standard Qab rotaray outputs.

for 8 rotary encoders it would be the best way to have a timer-IRQ at each 100µs to trigger then both the pin-reading and the encoder-maths.
That's the way I'm doing it on my Arduinos (MEGA: 100-250µs by a AVR Timer, DUE: 100µs by DueTimer), and both is working perfect:
http://www.mindstormsforum.de/viewtopic ... 624#p67236 (2nd code for Arduino)

Timer-IRQ is performing better than pinchange-interrupts if you have >4 encoders to monitor.

[davenull]

IMO 3 things have to be resolved for your system to get shortlisted:

a) your libs must be absolutely wiringPi and pigpio-compatible when linked all together - you'll probably have to fix that unconditionally !

b) real-time capable encoder readings implemented by a Timer interrupt on hardware level (not userpace like on Raspi)

c) 100$ for the assembled board plus 50$ shipping + VAT is unreasonable - for this money I could get all over 4 RaspberryPis 2.0 !
That's far beyond the pale.
Lowering wage costs and shipping costs is the topmost entrepreneur's duty (I know what I'm talking about as I have my own business):
Lower your retail price to about all over - at the very most - 80EUR (assembled) for the common market, inclusively shipping and VAT, that will be indispensible IMO for selling it to the EU.

[mikronauts]

Dave, you seem to be suffering from some wrong impressions.

1) I am not going to spend hours customizing RoboPi for you, I was just making suggestions that might help you. I was going to implement quadrature encoders in the API at some points anyway FOR ALL MY CLIENTS.

2) The price is what it is. I already told you how much it costs me to get them assembled, and the raw parts cost for the kit is very high (my cost on just the three IC's is almost $20 landed here).

3) I WOULD LOVE TO LOWER SHIPPING COSTS! Have not found a solution yet, shipping costs are very high from Canada to EU

4) I WOULD LOVE TO LOWER LABOR COSTS! Qualified techs expect $25+/hour here

5) You may be a small business, but you are based in EU, with lower shipping and labor costs, and I suspect you have not brought low quantity high parts cost add-on boards to market yourself.

6) $80 EU = ~ $88USD significantly less than my raw costs for parts, pcb, assembly and shipping never mind VAT, which would mean selling every unit at a large loss

7) I sell as a kit to try to keep the price low, and offer assembled units on request for those that need it

8) RPi is from the non-profit foundation,

9) Please take me of your short list, I was trying to help you address your requirements


PLEASE show me where I can buy 4x RPI 2's including shipping and VAT for $150USD, even though that is irrelevant as it is an apples vs oranges comparison.

You cannot compare the cost of a Pi, made in millions of units, to a low volume item

IMO 3 things have to be resolved for your system to get shortlisted:

a) your libs must be absolutely wiringPi and pigpio-compatible when linked all together - you'll probably have to fix that unconditionally !

b) real-time capable encoder readings implemented by a Timer interrupt on hardware level (not userpace like on Raspi)

c) 100$ for the assembled board plus 50$ shipping + VAT is unreasonable - for this money I could get all over 4 RaspberryPis 2.0 !
That's far beyond the pale.
Lowering wage costs and shipping costs is the topmost entrepreneur's duty (I know what I'm talking about as I have my own business):
Lower your retail price to about all over - at the very most - 80EUR (assembled) for the common market, inclusively shipping and VAT, that will be indispensible IMO for selling it to the EU.

[davenull]

you simply had to look for wage costs < 10$/h and lower shipping costs by having a European provider, sure!
and 150 $ plus VAT = 160 EUR
1 Raspi model 2 is about 42 EUR https://www.conrad.de/de/raspberry-pi-2 ... 16978.html

but ok, thanks for your input, then the RobotPi is too expensive unfortunately.

[davenull]

(cross over post)

[mikronauts]

I know, I wish I could sell it cheaper, I am keep looking for a good EU distribution channel.

Unfortunately that is what the couriers charge, and those are the skilled labor rates are here.

you simply had to look for wage costs < 10$/h and lower shipping costs by having a European provider, sure!
and 150 $ plus VAT = 160 EUR
1 Raspi model 2 is about 42 EUR https://www.conrad.de/de/raspberry-pi-2 ... 16978.html

but ok, thanks for your input, then the RobotPi is too expensive unfortunately.

[davenull]

ok, thank you for your input!

now are there any alternatives to RoboPi, delivering from Europe (EU)?

wanted:
robotics multi-IO shield providing plugs for external L298 H bridges (or even more powerful ones which I already have, on proprietary backpanes)
- to control 8 motors feat. rotary encoders
- plus extra digital (at least extra 16x) and analog pins (ADC 10-bit, at least 10x)
- plus at least one extra free i2c and UART for external devices (GPS, IMU, ...)

It's for an autonomous robot with 1 6DOF arm, all motors PID-controlled, 2 motors for odometry, so quick pin reading is required (all pins in polling cycles of about 100µs).
I am programming in C/C++ (g++, Raspbian Jessie, Geany IDE, wiringPi and gpio compatible, ), no Python.

Is there such a thing available? Perhaps even hooking up several different shields or backpanes?

[BMS Doug]

This kickstarter project might fill some of your needs.

[davenull]

indeed, Arduino Zero-based, Arduino IDE compatible libs, even 2 UART ports free - just curious about a free i2c and the RasPi-to-ZeroPi API interface though -
but over all:
awesome!