SerialUSB.print problem with configuration of external serial monitors

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SerialUSB.print problem with configuration of external serial monitors

(18 posts) (6 voices)

Started 5 years ago by JoshSanders
Latest reply from mbolivar

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JoshSanders
Member
Hi there!

Using Maple IDE 0.0.6 in Windows XP, I have been trying to send characters from the Maple board to serial monitor programs not included in the Maple IDE. I use the following code:
```
int inByte = 0; 

void setup() {
}

void loop() {
if (SerialUSB.available() > 0) {
    inByte = SerialUSB.read();
  SerialUSB.println("K");
}
}
```
When I use this with the Serial Monitor included in the IDE, sending any character results in feedback of the character "K". Using MATLAB or the free serial monitor available from http://www.compuphase.com/software_termite.htm I get no response.

Using an Arduino Duemilanove and the following similar code, I am able to get a "K" response from the IDE serial monitor, MATLAB and Termite.
```
int inByte = 0; 

void setup() {
  Serial.begin(115200);
}

void loop() {
if (Serial.available() > 0) {
    inByte = Serial.read();
  Serial.println("K");
}
}
```
I tried adding auto-linefeeds, changing the bit-rate to 9600, and using SerialUSB.print instead of SerialUSB.println.
Is there some subtle detail that I'm missing about how the serial port software should be configured differently for Maple?

Here are the settings used in Termite:
Port: COM12
Baud Rate: 115200
Data Bits: 8
Stop Bits: 1
Parity: None
Flow Control: None
Forward: None
Transmitted Text: Append Nothing
Local Echo: On

Thanks!
-Josh
Posted 5 years ago #
StephenFromNYC
Moderator

Fri September 24, 2010

Hello Josh-

I am glad to see that you are trying to develop MatLAB/Maple code. I spent some time trying to port some of my LabVIEW/Arduino code to the Maple. Some of the simpler code was easy to port, but some of my more intricate LabVIEW/Maple code still does not work.

Did you see my earlier post about my "reproducible" problem with SerialUSB.println() on a Windows XP SP3 system?

http://forums.leaflabs.com/topic.php?id=152

My problem was that the sketch failed when I used the Maple-IDE terminal, but it worked with external terminal apps.

I think most people who include descriptions of their Windows XP systems say they use SP3
You did not describe the service pack of your system:

http://forums.leaflabs.com/topic.php?id=145

Some suggestions (which I have not tested) are:

1) Try a different terminal program. Is there a reason you need to use Termite? Can HyperTerminal (also free) be used instead? Apparently, many of the SerialUSB experienced by Windows XP users are not observed when using Linux serial terminals.

2) Did you read the "Caveats and Changes" box found on the USB page of Maple docs:

http://leaflabs.com/docs/maple/usb/

I do not understand all the details yet, but using getDTR() and getRTS() might help you.

It is not clear why Arduino code works without worrying about the DTR and RTS lines. I need to do more reading.

3) I never have more than one USB device connected, but how many USB devices do you have connected to your system? When in doubt simplify.

4) My last idea is not very helpful, but you can wait until 0.0.7 comes out. I do not know if the documentation for SerialUSB will be any better, or if there will be more examples of how getDTR() and getRTS() are used to solve problems on different platforms.

I volunteered to be a tester of alpha 0.0.7 when it is released. It is possible to have both 0.0.6 and 0.0.7 on the same system. Apparently there is no interference. The one inconvenience I expect is that sketches need to be manually opened within the IDE.

Good luck,

Stephen from NYC

Posted 5 years ago #
JoshSanders
Member

Hi Stephen

I'm using SP3, and the Maple is the only USB device plugged in. I used Termite because I wanted to replicate my MATLAB problem so that troubleshooters wouldn't have to buy MATLAB in order to reproduce the problem on their systems.

Good call on the DTR and RTS - selecting "DTR/DSR" or "RTS/CTS" from the "Flow Control" menu in Termite fixes the problem.
Now all I have to do is figure out how to get MATLAB to do the same thing =p

In the interest of Arduino compatibility, is there a way to eliminate the flow control configuration requirement in Maple? Or is this an inflexible part of the hardware?

Thanks for your quick reply.
See y'all at Maker Faire!

~Josh

Posted 5 years ago #
snigelen
Member
I haven't tested but I guess something like this wold work in Matlab:
```
s = serial('/dev/ttyACM0');
s.FlowControl = 'hardware';
```
Posted 5 years ago #
JoshSanders
Member

There is an option to change the "flow control" property of a MATLAB serial port object to the setting "hardware" (default = "none").

According to the MATLAB documentation, this will use RTS/CTS. DTR/DSR is unsupported.

I get the following error when I try to write a byte to the Serial port:

'
>> fwrite(Ser, 'a')
??? Error using ==> serial.fwrite at 192
FWRITE cannot be called. The FlowControl property is set to 'hardware' and the Clear To Send (CTS) pin is high. This could indicate that the serial device may not be turned on, may not be connected, or does not use hardware handshaking.
'

The RTS/CTS setting in Termite works fine. . . I imagine the problem is probably a quirk on the MATLAB end, so I'll try to figure it out. In the meantime, is there a way to disable flow control on the Maple end to facilitate porting Arduino code in the future?

Sorry if I'm trivializing this - I'm still a newbie & ignorant of what it would take to do this =)

Posted 5 years ago #
StephenFromNYC
Moderator

Tuesday September 28, 2010

Hello,

Josh, once again, as a "still learning" LabVIEW programmer I am excited to hear about your MATLAB/Maple project. In full disclosure, I started working with Arduino Duemilanove in late 2009 and with the Maple (Rev 3 and IDE-0.0.6) this summer.

How much time have your spent using MATLAB? Do you have any experience working with MATLAB and other serial devices? Is this the first MATLAB/Maple program you are developing? Does your MATLAB code work on an Arduino?

Are you trying to communicate using SerialUSB() or SerialN()?

I am happy to share some ideas about working with LabVIEW and microcontrollers (both the Arduino and Maple) and serial communications over the USB wire (using the FTDI USB-serial driver for the Arduino and the SerialUSB functions for the Maple). I have minimal experience with MATLAB, so I do not know if my suggestions are transferrable to your MATLAB project.

I agree that using LabVIEW and MATLAB are nice because these apps have mature GUIs. This is very helpful if a client rolls eyes when given a data file (even when developing a simple command line program would answer the question much faster and therefore be a cheaper solution for the client).

gbulmer, when you work with your students do visual GUIs help them stay interested and connected to the projects? At what age do your students begin using data files in their programming projects? Do you use Processing with your students or another app? I am asking because I was asked to recommend a programming environment for children (ages 10+).

Using LabVIEW with the Arduino/Maple would be easier if compatible drivers were available. However, a "standard" driver does not exist.

In developing my LabVIEW/Arduino code I first created Arduino code which would talk to a simple serial terminal program such as HyperTerminal. Then I replaced the terminal program using Processing. This extra step with Processing was necessary to convince me that my Arduino code was working as expected at a higher rate. Using a terminal program I could not send commands to the microcontroller faster than 2X-3X a second. When both HyperTerminal and Processing worked I created the LabVIEW code. I used LabVIEW, because I wanted a more polished way to quickly graph my data.

Does Processing work well with the Maple? On this forum very few people discuss Processing. One exception:

http://forums.leaflabs.com/topic.php?id=197#post-1362

Josh, is CTS/RTS still a problem for you? You asked if it could be turned off. According to the USART page of docs the Maple does not use CTS/RTS (clear to send/ready to send) on Serial1 (but it does on Serial2 and Serial3).

Is there a reason why Serial1 does not implement CTS/RTS. Is there a reason why SerialUSB does not implement CTS/RTS?

Josh, I am glad my DTR/RTS suggestion worked so well on Termite. I do not know if you, in return, can help me with a current problem:

http://forums.leaflabs.com/topic.php?id=86&page=2#post-1420

Thanks for your time!

Stephen from NYC

Posted 5 years ago #
gbulmer
Moderator

StephenFromNYC:

gbulmer, when you work with your students do visual GUIs help them stay interested and connected to the projects? At what age do your students begin using data files in their programming projects? Do you use Processing with your students or another app? I am asking because I was asked to recommend a programming environment for children (ages 10+).

I deliberately chose to build simple robots, to get them interested, so their 'GUI' is physical atoms, not pixels :-)
My school students are 14 to 16. Part of the reason I run the workshops for schools is to give them a broader understanding of what they could do with technology while they are young enough to adjust their career and educational paths, but old enough that there are fewer health and safety issues (13 or younger is a different set of laws).

I have tried to side step the issue of a GUI in the past by showing them how to use Serial.print to create text in the serial monitor which they "paste" into Excel to get graphs. One student is very adept at this, and gets some great results.

I am now planning to take a friends 'Arduino-scope' written in Processing and use that for some things. Clearly, a MatLab/LabView system would be nice, but it has to be free.

I have written drivers which run on the Arduino which implements some of the physical computing board protocols for Scratch. I haven't made time to do as much with this as I had intended, but I do hope to move things along further before the end of this year.

I have designed and written more advanced physical computing interfaces, running on Arduino, for a fork of Scratch, but when I have emailed MIT (Leah Buechley) about supporting them in future Scratch developments (there is a huge set of changes coming) I got no response, so I am on hold with that area.

Does that help?

Posted 5 years ago #
StephenFromNYC
Moderator

Thursday September 30, 2010

Hello,

gbulmer, thanks for the Scratch referral. I had it bookmarked, but I never tried the software. Scratch works on Win/Mac OS/Linux. That is a great plus. I am glad Scratch supports Mac OS "Tiger" (10.4). A friend recommend GameMaker (released by yoyogames), but they do not support Mac OS 10.4. It is nice when educational software supports older systems, because you never know who is running what at home. If software requires the most recent OS version it prevents some students from writing programs at home. The digital divide once again.

I have not tried at Octave, SciLab, or FreeMat. From what I have read they differ in their compatibility with MatLAB. I do not know anything about their support of serial communications.

JoshSanders and snigelen, do you have any experience with these open source alternatives to MatLAB? How easy is it to develop applications which can communicate with micrcontrollers such as the Maple?

Thanks!

Stephen from NYC

Posted 5 years ago #
JoshSanders
Member

Ok, lots of questions. I'll do my best.

How much time have your spent using MATLAB?
I've used it for systems control and data analysis daily for 4 years.

Do you have any experience working with MATLAB and other serial devices?
Yes, I've controlled Arduino and these products:
http://www.pololu.com/catalog/product/1350
http://www.4dsystems.com.au/prod.php?id=79
http://shop.tomsrc.com/product_info.php?cPath=103_154&products_id=645

Is this the first MATLAB/Maple program you are developing?
Yes.

Does your MATLAB code work on an Arduino?
Yes.

http://en.wikipedia.org/wiki/Finite-state_machine
The code is a MATLAB controlled virtual state machine, allowing time stamps for events with sub-millisecond precision unavailable without a real-time OS. Events logged are opening and closing of solenoid valves, LED on and off, timers / scheduled waves ending, sound onset and offset, and more generally, analog values crossing thresholds or digital lines going high or low. Although TCP/IP transmission adds a small amount of temporal jitter, the state machine can also send packets to an IP address on state entry. We use this to control a proprietary $60K odor delivery system that can combine any of 128 monomolecular odorants, and deliver the mixture in pulses accurate to 10ms. The rationale for using the state machine framework is for ease of session protocol development in psychophysics and neuroscience laboratories where neural data is acquired with respect to precisely controlled events.
An example of this system using $6,000 worth of computers and national instruments cards / cables / breakout boxes (+ a major headache to set up and maintain):
http://brodylab.princeton.edu/bcontrol/index.php/Main_Page
My goal is to create an open, comparable system for less than the cost of an ipod. (I call it project B-pod). It already works on Arduino Mega + ethernet shield - the only limitation is that Arduino takes 100 microseconds to sample an analog channel. Presently, our core setup uses 3 analog inputs (IR photogates) to trigger state changes on threshold crossing and 200us to execute state changes - so I'm still under 1ms. However, in our laboratory, we sometimes use more than 3 photogates and would like to use accelerometers / IMUs in the future to trigger state changes - so we'll need faster analog acquisition. Also, the benefit of 32 bit math will help shave time off state transitions, since all timestamps are long int and we're computing durations on-board to minimize write time over Serial.

Are you trying to communicate using SerialUSB() or SerialN()?
I've only used SerialUSB. I'll try SerialN.

"I agree that using LabVIEW and MATLAB are nice because these apps have mature GUIs."
Irrespective of GUI, we use MATLAB for ease of data analysis with the statistics libraries, and for ease of data handling (built-in matrix operations, etc). . . and also for historical reasons. Most science laboratories in the USA use Matlab for instrumentation, with Labview a close second - if you want to collaborate with other scientists on a project, you need a common language. Science would go nowhere if every collaboration started out with "Everything I've done is in Igor Pro, so you'll have to learn that first". Sadly, the scientific community's shelling point is very expensive, closed source, proprietary software. Rather than be an idealist, I'll stick with it for now, to maximize the benefit of open hardware in the hands of scientists. Encouraging them to learn a new language can come later. I'm thinking python.

Josh, is CTS/RTS still a problem for you?
Yes, I haven't found a workaround. Again, my error is:

>> fwrite(Ser, 'a')
??? Error using ==> serial.fwrite at 192
FWRITE cannot be called. The FlowControl property is set to 'hardware' and the Clear To Send (CTS) pin is high. This could indicate that the serial device may not be turned on, may not be connected, or does not use hardware handshaking.

Can help me with a current problem:?
I'm also waiting with baited breath for the micros() command to be implemented. Sadly, my area of expertise is Biology - it would take me months to get up to speed with Maple's toolchain under the hood so I can improve the source, so for now I'm just a user =(

Do you have any experience with these open source alternatives to MatLAB?
No, our lab is aware of them, Octave being the best contender - however, Octave does not have support for most of the "toolboxes" we use. (i.e. psychophysics toolbox, instrument control toolbox, statistics toolbox, image processing toolbox, etc.)

Finally, I'll re-iterate the bug I'm stuck on:
Matlab's Instrument Control Toolbox allows creation of a serial port object which can communicate with Arduino and the other hardware I listed above, but not Maple.

Thanks guys!
I'm excited to promote awareness and use of open hardware in the laboratory!

Josh Sanders
Kepecs Lab
Cold Spring Harbor Laboratory
http://kepecslab.cshl.edu/AK_research.html

Posted 5 years ago #
StephenFromNYC
Moderator

Thursday September 30, 2010

Hello,

I have been using LabVIEW and the Arduino for the last year, so I am very new to computer control of instrumentation and microcontrollers. I jumped onto the Maple when I saw the improved ADC and the faster clock speed.

One reason I have not spent a lot of time recently with porting my LabVIEW/Arduino code to the Maple is that "LabVIEW 2009" supports only 1 millisecond time intervals. It is possible that sub-millisecond control may be available on "LabVIEW Real Time". As you may know National Instruments sets their prices on the high side of affordable.

Josh, I appreciate the need to stick with commercial software for which third parties write toolboxes. I have not looked myself (being lazy again), but do you know if Octave or the other MATLAB clones support microsecond (ie sub-millisecond) timings? If I could trigger analog sensor readings every 100 microseconds on the Maple I would be very happy.

Does MATLAB officially "support" the Arduino, or are you simply using serial communications?

In your project SerialN may work when SerialUSB fails. Do NOT use Serial1, because Serial1 does NOT support CTS and RTS (according to the USART doc page). However, both Serial2 and Serial3 on the Maple support CTS and RTS. Unfortunately the USART doc page does not have any code examples.

Josh, mbolivar said he plans to respond to my questions about the uses of SerialUSB vs SerialN.

http://forums.leaflabs.com/topic.php?id=206

I do not know if he will have time before IDE 0.0.7 is released, but stay tuned!

Many problems may eventually disappear if the Maple Rev 6 implements a driverless USB serial model.

http://forums.leaflabs.com/topic.php?id=207

Josh, I realize the new Arduino UNO is not fast enough for your needs. However, do you know if the driverless USB serisl model (LUFA?) used by the Uno is compatible with your current MATLAB/Arduino code? If your Duemilanove/Mega code ports easily to the UNO it may be a reason to be optimistic about Maple Rev 6.

Josh, is the ATmega chip used on the Arduino Mega faster than the ATmega328 used on the Duemilanove/UNO? Would this solve your faster ADC needs for B-pod?

It is users like us who push the limits of the hardware and software which will make the Maple platform more robust for all users.

Thanks!

Stephen from NYC

Posted 5 years ago #
gbulmer
Moderator

is the ATmega chip used on the Arduino Mega faster than the ATmega328 used on the Duemilanove/UNO

I am 96% confident that the ADC in the ATmega1280 has the same operating parameters as the ATmega328 ADC, so they should take the same amount of time to sample and convert.

Posted 5 years ago #
JoshSanders
Member

I finally figured it out-

the MATLAB serial object has a field "RequestToSend", that is off by default.
Setting this to 'on' makes incoming bytes show up properly.
It's funny that Serial communication with Arduino doesn't have this issue. . .
Anyway, problem solved!
Initialize the serial port from the MATLAB end with this line of code:
Ser = serial('COM12', 'BaudRate', 9600, 'DataBits', 8, 'Timeout', 3, 'RequestToSend', 'on');

Cheers,
Josh

Posted 5 years ago #
gbulmer
Moderator

Well done! That sounds truly frustrating.

Request To Send is an RS232 serial protocol signal. There can be a wire dedicated to carrying that signal. It can be used to manage the flow of data at the hardware level. Interestingly, the FTDI USB to Serial hardware on the old Arduino does implement that signal, but the Arduino's ATmega microcontroller isn't connected to the pin.

RTS, partnered with Clear To Send (CTS) is so popular for RS232 and serial communications that the FTDI USB to TTL-Serial cables, which only expose 6 signals, include RTS and CTS as two of them (the others are Transmit data, Receive Data, Ground, and Vcc).

I tried debugging something like this a couple of years ago. I didn't have access to a USB sniffer, but I did have a Mac with DTrace. DTrace lets you see inside programs, including the operating system kernel. I wrote quite a lot of DTrace script to decode the exchanges between a program and a USB device (the host program uses ioctl to manipulate RTS, CTS, baud rate, etc.). Without DTrace, I would have had an impossible time.

Posted 4 years ago #
poslathian
LeafLabs

on the maple, end we use DTR/RTS to determine when sends block and when they dont. This is probably why you needed it for maple but not arduino. This is being changed to a default nonblocking (with blocking enable-able in SerialUSB.begin()) configuration.

Posted 4 years ago #
gbulmer
Moderator

Cuddeback was posting spam as part of their signature.

Posted 4 years ago #

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