This post is to hopefully document all the available broadcasts and variable usage that ScratchGPIO understands and responds to
Extra Blocks for specific Hardware
Several add-on boards can be connected to a Pi and be automatically recognised and used
Analog Input/Output based on 8591Chip
Any board containing this chip can be used to read 0-5V analogue voltages and to control one variable output
Scratch Variable “bug”
Although using variables is necessary once you start writing complex scripts, there is a “bug” or a “feature” (depending on yourpoint of view) in the way that Scratch sends out variable changes to any external programs.
If you say broadcast pin11On then Scratch will always send Pin11On out to any listening programs
But if you use a variable called Pin11 and say set Pin11 to On then it only sends this information out if the previous value of Pin11 variable was not On i.e. only changes are sent out
This code will not switch pin11 on the second time as the variable has not changed from its previous value.
One workaround is to use the green join block and broadcast any variables
This method will ensure than any variable changes are always sent out
HI
I have PiRingo board and have been using it with scratch and GPIO ver 4.1.09a
I can use all the leds and set then on or off and alter powerlevels ok, but I haven’t been able to figure out how to read the push button values. I can’t get any changing output from the sensor blocks, and not 100% certain which one to use switch1§, switch2 or button pressed.
Can you give an example of use of reading the button values pushed/not pushed please.
Simply try
forever
speak sensor switch1 for 2 seconds
and see if it goes between 0 an 1
I’ll dig one of mine out and make sure it works 🙂
Simon
Thanks working fine!
Further to my previous question, I have now completed a program which demonstrates the use of the PiRingo ChristmasWreath/Traffic Light board using both leds and push buttons. To overcome the problems of using variables to send commands to the gpio interface I have used List variables. Once set up, these give a very fast response and enable fast moving patterns similar to those achieved in the python demo flash.py program.
It is downloadable with a browser from http://r.newman.ch/rpi/circlelight.sb.zip
Code looks interesting – I’ll have to try it out after I’ve finished adding the PiMatrix board in 🙂
Simon
Simon, I’ve now built a new Raspbian system from a new noobs sd card in the hope that this will somehow allow your dev version of scratchgpio4 work for me with the steppers. No change I’m afraid. I see others have got it working which is encouraging. I am at a complete loss here. Through scratch I can manually turn on/off each of pins 11, 12, 13, 15 but it’s no go for the “broadcast stepper, set motorA to 100, etc. I was wondering if I had actually got all the Scratch features ( eg variable names) that you are using. I noticed in your Visual Commands Guide there are some functions that use “sensor value” such as “say [Version] sensor value for 2 secs” to display the scratch GPIO version. I assume these sensor based function are something you have built into the scratchgpiox. The allowable variables for the sensor value on my system are fixed and limited to the basic list (slider, etc…….) .Maybe one needs to build these oneself using the MESH capability. I am sure you must be fed up with this but am baffled by the stepper situation, particularly when the python stepper program work fine as does my DC motor side. You are welcome to try and remotely access my Pi and take a look.
Mike S.
I am just wondering if you know about the Scratch “feature” that means that once you set a variable – it never bothers to repeat its value across MESH?
In my scripts I do this
On GreenFlag
broadcast Stepper
set MotorA to 0
On Spacebar
Set MotorA to 100
If that doesn’t work – can you modify that simple sequence from before to make all the leds go on and off sequance.
Once you’ve done that – can you change the waits from 1 sec to 0.1 sec and at least get the stepper to turn that way 🙂
Simon
Like this
On GreenFlag
broadcast AllOff
forever
broadcast pin15off
broadcast pin11on
wait 0.1
broadcast pin11off
broadcast pin12on
wait 0.1
broadcast pin12off
broadcast pin13on
wait 0.1
broadcast pin13off
broadcast pin15on
wait 0.1
11:00 am EST
Simon – “Houston, we have lift-off”
Your first script worked. The essence of the problem and the many hours in head scratching was totally on my side with the opening BROADCAST statement. I had created a variable call STEPPER and with the mouse move this on top of the existing “set pins” variable in the BROADCAST box. I did not see any other way at the time to add STEPPER.
The STEPPER variable block seemed to set in nicely on top of the “setpins” variable name so I assumed it had “taken” and all was well. This time I again clicked the BROADCAST pull down menu and noticed, in addition to setpins they was a “new” item for selection. Clicking on new a “Message Name” block appeared into which I typed “Stepper”. On clicking the “on green flag” the stepper started stepping. Hurrah!
So, Simon, many thanks for sticking with me on this one. It’s very much appreciated.
Now, on those “sensor value” blocks, does the MESH function need to be “activated” in order to add different variable names to the preset one ( eg to add “Version” to display the scratchGPIO version). I did discover some instruction to activation MESH on a Manchester U. Site called Piface digital. http:/pi.cs.man.ac.uk/download/EnablingMeshInScratch.pdf
I followed their instructions but not sure if I activated it or not. Some of us need some good doc(s) on the inner working of Scratch for things like MESH and it’s capabilities. You likely use all this in your Scratchgpio development.
Anyway, thanks again for all your help.
Mike S.
Yippee 🙂
All this work is not lost as it all helps the next person and it makes me not assume things 🙂
Right – Scratch MESH 101 🙂
Ignore the sensors above the line – these relate to a thing called the PicoBoard and that’s a compeltely differentconcept
MESH is the way Scratch can talk to external programs by sending data using TCP/IP (same as internet packets) to and from other computers on the same network. IF you Google Scratch Mesh you’ll find out details
So we use MESH (or Remote Sensor Connections or RSC as its also know) to just send these packets to the RaspberryPi itself and then run a Python program to listen and respond to them. Scratch sends broadcasts and variable changes out this way – my Python prog listens and acts on them to control GPIO pins and also looks for changes in any pins used for input and sends them back to Scratch using TCP/IP and Scratch can read them as sensor values. This is used to detect switchs and things like Ultrasonic or IR detectors.
All this is done automagically for you by my launch script which launches the Python handler program, then launches Scratch and automatically opens up the rsc.sb script in Documents/ Scratch Projects which because it was last saved with RSC enabled, then it automatically re-enables it. This way Scratch is all set up ready to communicate with the Python handler running in background.
Hope this info helps but basiscally its all been done for you 🙂
Simon
PS My code was originally forked from the original PiFace code – its the universal way of communicating with Scratch 1.4
Thanks Simon, your MESH overview is very interesting and good to know of.
I have been trying out items in your Visual Command List, in particular the ones that use the “say XX sensor value for 2 secs”. I got the “GetTime” and the scratch GPIO “Version” work OK. Very useful.
However, I could not get the “say ipaddress” one working, mainly because after forming the variable “ipaddress” ( as I did for fulldatetime, hours, minutes and Version) I could not get the darn thing to appear in the pulldown parameter selection menu in order to select it for XX in the “say XX sensor value for 2 sec” command. In fact, sometimes the XX pull down list does and then doesn’t show any of these variables, just shows the “as supplied list). Things seem a little bit flaky in this global variable area, maybe its a timing thing. I usually “Quit” scratch plus reboot to reset everything, but still no “ipaddress” appears in the list.
Wonder if anyone else has experienced this? As I mention before I have an up-to-date raspbian system. Great to finally have the stepper working on Scratch
Any thoughts?
Mike S.
I’ll check the IPAddress handling – your the 1st person to ever tell me that they noticed those commands and tried them 🙂
It should be completely sufficient to just quite Scratch and restart ScratchGPIO as the launching process kilss any previous running process and starts again.
Reboot would be very much a last resort and I personally have never had to do that.
If you want to see what is happening in the background then you can just launch the handler seperately using LX terminal
sudo python /home/pi/scratchgpio4/scratchgpio_handler4.py
and then run NORMAL Scratch (NOT SCRATCHGPIO) and load in /home/pi/Documents/Scratch Projects/rsc.sb (or any other saved ScratchGPIO script that enables RSC)
You can then look at the Python handler programming running and spot if any errors are happening but its normally pretty boring (unless I’ve accidently left debugging enabled”)
Simon
Simon, did not get a lift-off with the first command: sudo python home/pi/…………
here is LXterm screen shot. Tried it several times. Maybe something on my side needs turning on. Looks like you debug is enabled. Should it be disables?
pi@raspberrypi ~ $ sudo python /home/pi/scratchgpio4/scratchgpio_handler4.py
Board Revision 2
Debug enabled
2
PiGlow init
i2cbus: 1
No PiGlow Detected
No Compass Detected
No pcaPwm Detected
No AdaMatrix Detected
No PiMatrix Detected
PATH: /home/pi/scratchgpio4
Starting to connect… Trying
There was an error connecting to Scratch!
I couldn’t find a Mesh session at host: 127.0.0.1, port: 42001
Trying
There was an error connecting to Scratch!
I couldn’t find a Mesh session at host: 127.0.0.1, port: 42001
Trying
There was an error connecting to Scratch!
I couldn’t find a Mesh session at host: 127.0.0.1, port: 42001
Trying
above keeps repeatting until do ctrl+C
Mike S.
if you’d like to try part 2 of the instructions
“and then run NORMAL Scratch (NOT SCRATCHGPIO) and load in /home/pi/Documents/Scratch Projects/rsc.sb (or any other saved ScratchGPIO script that enables RSC)”
🙂
Until my Python prog sees a Scratch session with RSC/Mesh enabled – its just sits there waiting for one to appear 🙂
Simon
Simon, assume by “load in” you mean execute rsc.sb?
Whats the secret to cd’ing to Scratch Projects? Its two words with no joining underscore so get “bash: cd: Scratch: no such file or Dir”
Mike S
No-run scratch (normal not scratchgpio) and load rsc scratch project 🙂
You are over thinking 🙂
Simon
No need for this-see other reply 🙂
Simon, forget last reply, went through ‘file manager’ and executed rsc.sb from there (double-click).
Looking in ‘task manager’ though, don’t see rsc.sb running……………?
What next?
You’ve wandered off the reservation -see other reply 🙂
Its a lot simpler then your making it 🙂
5:15 pm EST
Got it! Thanks. Here’s the result. By the way, talking of reservations, we have a real one with a casino about 45 mins north of us!
OK, given whats below, what exactly am I looking for re possible errors?
Maybe I have to try more of the items (like IPaddress) from the
“visual commands set?
MIke S
Result
No PiMatrix Detected
PATH: /home/pi/scratchgpio4
Starting to connect… Trying
Connected!
Running….
pin 7 changed to digital out from unused
(‘pin’, 7, ‘set to’, 0.0)
pin 8 changed to digital out from unused
(‘pin’, 8, ‘set to’, 0.0)
pin 10 changed to digital out from unused
(‘pin’, 10, ‘set to’, 0.0)
pin 19 changed to digital out from unused
(‘pin’, 19, ‘set to’, 0.0)
pin 21 changed to digital out from unused
(‘pin’, 21, ‘set to’, 0.0)
pin 22 changed to digital out from unused
(‘pin’, 22, ‘set to’, 0.0)
pin 23 changed to digital out from unused
(‘pin’, 23, ‘set to’, 0)
pin 24 changed to digital out from unused
more of the same displays ending in pin 5 msg.
It was just in case there was a glaring error message. I’ll power up and church it out at my end now 🙂
(It’s no hidden under a more item is it?)
5:27 pm EST
Simon, here’s first few lines after the sudo etc etc is executed. Debug is “On”/
MIke S.
pi@raspberrypi ~/Documents/Python_Projects $ sudo python /home/pi/scratchgpio4/scratchgpio_handler4.py
Board Revision 2
Debug enabled
2
PiGlow init
i2cbus: 1
No PiGlow Detected
No Compass Detected
No pcaPwm Detected
No AdaMatrix Detected
No PiMatrix Detected
PATH: /home/pi/scratchgpio4
Starting to connect… Trying
Connected!
Running….
pin 7 changed to digital out from unused
(‘pin’, 7, ‘set to’, 0.0)
Hi Mike
I just tried it and it worked for me
On GreenFlag
broadcast GetIp
And I then have a sensor value called ipaddress
Simon
What do you mean by “Debug is ON”??? What Debug are you reffering to?
Simon
Debug On – its superfluous, only noticing your python pgm said “Debug enabled”. Should have not added it. Mike S.
To test the IPaddress piece again, should I open a scratchgpio4 session or just use the scratch session opened by rsc?
I’ve lost the plot myself now 🙂
i think (for whatever reason) your setup is not in the same state as mine (And since I have 4 different ScratchGPIO V4, V4dev, V4DevDev and V5Dev) I think the fault is at my end 🙂
The IpAddress isn’t very useful so I think its just best to leave it alone – at least the datetime works 🙂
Forget everything about running the python handler manually and stick to the desktop icons – I’m nearly there on releasing V5 with all recent updates so we should be good to go when I do that 🙂
Simon
Simon, OK, good suggestion.
I did try IPaddress and the Version again on the scratch session opened by RSC. Neither worked initially with non of the new variables showing in the list, but shortly thereafter they magically appeared. So IPaddress did work as did version. Seems to be delays in the custom variables (version, ipaddress, etc) showing up. But no matter as you say – “on the scratchGPIO5!.
(Whats in gpio5?)
Mike S
Basically just extra support for add-on boards and revert the default pin state back to what I had origannly 11,12,13,15,16,18 as outputs and 7 and 22 as inputs but with internal pull-up resistors enabled so that all people have to do is connect a switch between them and ground.
The delay is very wierd but just to note – they won’t show up unless you do the approriate broadcast -i.e they are not there until you ask for a reading and the reading takes 0.1 sec to happen
Simon
This is awesome! Incredibly easy to get it up and running for simple pushbuttons and controlling LEDs. Do you have any more details or documentation on reading analog inputs? Would it be possible to get ScratchGPIO working with any arbitrary ADC and not just the 8591? Sorry if this is a dumb question, I’m used to Arduino and spoiled by the built-in ADC, and have yet to try using an external one with the Pi.
No 😦 Each ADC would need coding up unfortunately
Simon
Ok – how about the blocks for the ultrasonic sensor – are those written for a specific model number, or do ultrasonic sensors all follow the same protocol? (again, sorry for the amateur questions)
The cheap HR-04 ones are all the same https://cymplecy.wordpress.com/ultrasonic-sensor/
MAKE SURE you wire up resistors as you will blow your Pi up as it can’t handle 5V – only 3.3V
Ok – so I’m trying to get the 8591 working based on the code above. I’ve found some wiring diagrams – for example here:
http://blog.jacobean.net/?p=258
And it looks like it mostly consists of hooking up the proper V+ and GND connections (although I’ve seen conflicting information about whether to use 3.3 or 5V for VDD…the chip’s data sheet says “operating supply voltage 2.5V to 6V”…either away I assume you want to use 3.3V for the analog reference VREF), along with the SCL and SDA pins on the Pi.
However, I’m not sure if I have the Scratch code right. The “say” block has a bunch of options in a drop-down menu (slider, light, sound etc) but there’s no “adc1” option, nor is there a “new” option so I can type in my own.
Ideally I’d like to use the number as a variable in the program – for example, read in from an analog distance sensor and use that to steer a sprite left or right. Any suggestions on how to get this running properly in Version 5? As always, really appreciate the help and effort you put into this!
I just use a pre-built prototype board by 4tronix so I don’t know how the hardware is wired up and the board isn’t on market yet.
If its wired up right, it should be autodetected by the Scratch handler and the adc1..4 values will just appear in the sensor values like pins do.
best thing would be to make sure its appearing.
I’ll try and dig my board out and jsut check the code is still working Ok but I’ve got a backlog of requests at the moment and a lot of DIY to do at home 🙂
Simon
Ok – I’ll see if I can get the chip working in Python in the meantime, so I can make sure I actually have it wired up correctly.
Ta 🙂
Just tried it – worked as I said – adc1..4 just appear as sensor values – my board is detected at address 48
Simon
Dumb question. What does “detected at address 48” mean, and how would I check that?
I love what you are doing here. I found it through a link from a tutorial page here:
http://computers.tutsplus.com/tutorials/learn-how-to-use-raspberry-pi-gpio-pins-with-scratch–mac-59941
That page has a nifty little game that uses ScratchGPIO, and it works fine as written. However, to increase my understanding, I have been trying various simple changes, and I am stumped on one of them. Maybe I don’t know which pins are allowable inputs in ScratchGPIO. The game uses push buttons attached to pins 3 and 5 to move the cat. However, if I try to change which pins are used, (7 and 8 for example) and change the wires to connect to those pins, the cat just stutters and the buttons do nothing. They behave as if they are getting constant 0 values (i.e. not pulled high) because if I change one of the equations to check if the pin value is something other than zero, then the one that is still set to zero moves the cat.
Any explanation would be appreciated. If I can figure this out, I plan to use it with a local young person I am teaching to program.
Thanks,
-Steve
As a first check – re-install latest ScratchGPIO as that article refers to old V4 and some things have changed since then (V4 didn’t work out so I effectively went back to V3 but called it V5 🙂
So download from here https://cymplecy.wordpress.com/scratchgpio/scratch-raspberrypi-gpio/ try your script out – and come back if it doesn’t work please 🙂