USB TTL Module v1 Guide Chapter 2

3.6 Resetting the USB TTL Module Sometimes it’s useful to be able to reset the Module without unplugging the USB lead. To reset the Module and Serial Port click on the Reset toolbar icon or press CTRL+R. Doing this is equivalent to sending a Break in standard serial communications. 4. Using the USB TTL Module Programmatically From An Experiment Generator Or Your Own Software 4.1 Basic Output Event Marking Using a Serial Terminal Using the USB TTL Module from a serial terminal provides an opportunity for you to get a feel for how you read inputs and output event marks. We recommend the free Tera Term terminal software for this purpose however any terminal software that supports a serial port should work. Before you attempt to connect to the USB TTL Module ensure that all other software using the serial port it is assigned to be closed as only one application can use that port at a time. This also includes the configuration utility. Before you can use the USB TTL Module you will need to connect to it using the COM port which you installed it on. In this example COM26. You will need to configure the terminal software to use the communication settings shown: Baud rate: Data: Parity: Stop: Flow control: 115,200 8 bit None 1 bit None Once connected you will need to initialise it by sending the Module two RR bytes which resets the serial port and clears all TTL Output Lines. To check that the Module has been initialised and reset correctly send type ## bytes. The Module should reply with XX as shown. You’ll note that as the Module responds to two bytes as you press the second # it responds. You do not need to press return. The Module should only need to be initialised when it is first connected by sending it RR. However you can also use RR when ending an experiment to clear all lines and reset the Module. Once initialised to turn on all TTL Output Lines, i.e. 1~8 type the hex value FF as shown. The red LED on the Module will then illuminate and any equipment connected will show a TTL +5V signal on all lines. Note that the Output Lines stay on, or latch. To turn them off you need to send another hex value to the Module, e.g. 00. Again this has to be a hex byte pair. It’s crucial to ensure that you send hex pairs of byes, or characters, as otherwise the Module may get out of sync and will only respond when a second byte is sent. All hex byte pairs should be sent in capitals. To work out which lines you wish to turn on you can use the Configuration Utility to construct a hex value. Two byte hex Output values can range from (hex), 0~255 (dec), 00~FF 00000000~11111111 (bin) to represent the status of each Output Line on the Output Port. To convert from a binary on|off bit pattern simply convert to hex using a calculator. 4.2 Basic TTL Input Using a Serial Terminal Receiving TTL input from the USB TTL Module is straightforward. You should bear in mind that your own software will need to constantly monitor the serial port for input as this will happen asynchronously. That is, it can happen at any time. If you are simply event marking using the Module, i.e. outputting from your experiment generator or own software you do not need to monitor for inputs at all. Once connected and initialised (see section 4.1) the Module is ready to send you TTL Input Port Values encoded as two byte hex strings. Here TTL Input Line 1 has been sent high (+5V). Unless there is a line change no other byte pairs will be sent from the Module. When there is a change on the Input Port a new hex pair will be sent. In this example 00 indicates that all Input Ports lines have all gone to 0V or no inputs. If there is a pulse on a given Input Line then a series of hex byte pairs will be sent. In this example Input Line 1 is going from 1 to 0 or +5v to 0V repeatedly. 4.3 Tips for Using the USB TTL Module With an Experiment Generator or Your Own Software Using the USB TTL Module should be fairly straight forward for those with a background in programming. The information below summarises a series of tips for using the USB TTL Module effectively for simple event marking. WARNING: The Black Box ToolKit Ltd cannot be held liable for any damage caused to devices through use of the USB TTL Module howsoever caused. By using the USB TTL Module you accept sole responsibility for any subsequent damage. The end user should evaluate fitness for purpose prior to using the USB TTL Module with any given device. The Module is designed for use in research environments. Physical connection: • • • • • Use a USB port which is directly connected to the motherboard Try and always use the same USB port Do not use USB hubs or switches to connect the Module Do not use high bandwidth USB devices together with the Module and do not leave them connected to any USB ports on your system, e.g. USB memory sticks, external hard drives etc. Use the supplied high quality USB cable Before use you should to ensure that: • • • The Serial Port Driver has been installed (section 2.1) and you know what COM port the Module has been assigned to The Serial Port Driver has been configured and the latency set to 1mS (section 2.3) You have validated Event Marking Latency using the Configuration Utility (section 3.2) When using you should bear in mind that: • The Module should be opened with the following parameters: 115200, 8, N, 1 Baud rate: Data: Parity: Stop: Flow control: • 115,200 8 bit None 1 bit None Only one application can access one serial port at a time (this includes the Configuration Utility). If two are open you will receive an error (section 4.1) • • • • • • • • • Once connected you will need to initialise it by sending the Module RR. Ideally you should do this at the start of each experiment and optionally at the end of each experiment to ensure that all TTL Output Lines are cleared on exit For event marking send two hex bytes in capitals, e.g. FF to turn all output lines on (section 4.1) Output Lines stay on or latch when activated. To turn them off you need to send another hex value to the Module, e.g. 00. Again this has to be a hex byte pair (section 4.1) Only TTL Input Line changes are reported in order to reduce latency to below 1mS (section 4.2) It is possible to use the Module asynchronously for both input and output. However any two byte output must be completed before input can resume, i.e. outputs are blocking If you are monitoring the serial port for input, i.e. TTL signals being fed INTO the Module you will need to do so asynchronously as two byte reports can come at any time (section 4.2) Ensure that you always send and receive two hex bytes otherwise this may cause the Module to hang until you send or receive a second byte Once the COM port is opened you should not open and close it again. You should only open it once and close it once in the course of an event marking session regardless of how many event marking hex byte pairs you send To retrieve the firmware version number send the byte pair VE to the module. Firmware updates may be available from the USB TTL Module area of our support website Examples of event marking a stimulus onset and duration are shown below for several popular packages. Note that these are simple examples and that you are responsible for proper implementation as we cannot provide detailed programming advice for third party systems. PsychoPy E-Prime® MATLAB import serial ser = serial.Serial(0, 115200, timeout=1) ser.write('01') ser.write('00') ser.close() Serial.WriteString “01” Serial.WriteString “00” s = serial('COM1'); set(s, 'BaudRate', 115200, 'DataBits', 8, 'StopBits', 1, 'Parity', 'none') fprintf(s, '01'); fprintf(s, '00'); fclose(s) You are also advised to consult the appropriate documentation for writing byte pairs in hex, e.g. WriteByte(0x01) in MATLAB. When developing it is advisable to check that the Module is working correctly in a serial terminal such as Tera Term (section 4). You should bear in mind that the TTL Module is locked to the time domain of your Experiment Generator, i.e. when you instruct it to produce a TTL signal you are relying on your Experiment Generator to output the serial bytes required at the time you request them. For an example of what this may mean for your experiment you are advised to consult section 5 of this guide. 5. Worked Examples Using E-Prime® 5.1 Event Marking Using Task Events E-Prime® 2.0 and above allows you to easily event mark using Task Events through EPrimes standard property dialogs. Psychology Software Tools describes Task Events as follows: “Task Events improve upon E-Prime 2.0 Professional's ability to communicate with external devices by offering a variety of trigger signals to be sent when specific time-critical events occur during an experiment. Previous versions of EPrime provided some limited support for this type of communication, but only by way of complex design and/or advanced E-Basic scripting techniques. These capabilities can now be achieved using the E-Studio graphical user interface, with greater precision and without the need to write InLine script.” You should bear in mind that the TTL module is time-locked, or synchronous, to the EPrime® time domain, i.e. when you instruct it to produce a TTL signal you are relying on EPrime® to output the serial bytes required at the time you request them. This also applies to any other Experiment Generator or software that you have written yourself. The TTL Module is simply designed to offer a method to produce and receive TTL signals. The TTL Module has no in-built timing mechanisms and it should be thought of as an alternative to using a parallel port. In practical terms this means that you are reliant on your software producing an event mark at the correct time just as you would be if you were using a parallel port. For example, if you choose to event mark an image onset you are reliant on your software sending the required serial bytes to the TTL Module immediately prior to displaying the image. If you wish to base your event marking on the physical appearance of stimuli in the real world rather than the time you requested them be shown you will need to make use of timing validation hardware such as the Black Box ToolKit v2 or the mBBTK v1 which is specifically designed for event marking physical stimuli across multiple modalities and TTL I/O channels. The Black Box ToolKit Ltd cannot accept any responsibility for inaccurate event marking that are as a result of bugs in your chosen software, poor scripting practices or Operating System issues. THE FOLLOWING EXAMPLE SCRIPT IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE EXAMPLE SCRIPT OR THE USE OR OTHER DEALINGS IN THE EXAMPLE SCRIPT. Before you can begin you will need to ensure you have added your USB TTL Modules serial port to the list of available devices. For consistency we have called the device Serial. You will need to ensure that the selected COM port matches that of the USB TTL Module on your own system. CTRL+E will bring up the Experiment Object Properties Dialog. In this examples structure view we can see a simple experiment that displays a stimulus image a number of times. Each stimulus is proceeded by a fixation and followed by an ISI image. You should note at the top and the tail of the experiment there are InLine scripts to initialise and reset the TTL Module. Both pieces of script reset the TTL Module and clear any TTL inputs or outputs. The TTL Module is reset by sending the two bytes RR: Serial.WriteString "RR" To use a Task Event to event mark click on the stimulus images properties button. Click on the Task Events tab and then on the Add… button to add a new event. Typically you would select the OnsetTime option for the Stimulus image object. For further information on the available events you should consult Psychology Software Tools website. Next click on the more button … and select the Serial port object so that you can write to the USB TTL Module. Finally fill in the Options as shown. Stimulus.OnsetTime In this example: Custom: 01 means that TTL Output Line will be high (+5V), or on, while the stimulus is displayed. To turn off the event marking signal you should add a second Task Event as shown but under custom set it to 00: Custom: 00 This will clear all the TTL Output event marking lines at the stimulus images offset. When your experiment runs there will now be an event mark on TTL Out 1 whenever the stimulus image is requested to be shown by E-Prime®. For more details on Task Events and event marking using InLine script calls you should consult the E-Prime® User Guide and online Knowledge Base, e.g. http://www.pstnet.com/support/kb.asp?TopicID=1318. Please note that the Black Box ToolKit Ltd cannot provide support for third party software such as E-Prime. Example scripts can be downloaded from our support website but are provided on an “as is” basis. 5.2 Input Triggering Using Your Own Scripts The TTL Module allows you to wait for an incoming TTL input trigger and then perform an action. Typically this feature is used to show a stimulus when a trigger is received, e.g. in fMRI studies. In this example as before there are two pieces of InLineScript that reset the USB TTL Module and are called at the start and end of the experiment. Note that just after the fixation object there is a piece of InLine script that we have called: WaitStimStartSignal Experiment execution will wait here until there is a TTL input on the USB TTL module. In this example execution will pause at the InLine code as the Do While Loop waits for any input change signalled by two incoming serial bytes from the USB TTL Module. So for example if TTL In 1 went high (+5V) then bytes 01 would be sent via serial to EPrime, the holding loop exited and the stimulus shown. Dim incomingBytes(1) As Integer Dim bytesRead As Long Serial.FlushInBuffer bytesRead = Serial.ReadBytes(incomingBytes) Do While Serial.InputCount = 0 'look for incoming bytes on the serial port that indicates a trigger signal bytesRead = Serial.ReadBytes(incomingBytes) Loop A typical example of a holding loop is shown opposite. For more details on using InLine script calls you should consult the E-Prime® User Guide and online Knowledge Base, e.g. http://www.pstnet.com/support/kb.asp?TopicID=1318. Please note that the Black Box ToolKit Ltd cannot provide support for third party software such as E-Prime. Example scripts can be downloaded from our support website but are provided on an “as is” basis. 6. Technical Specifications 6.1 Hardware Specifications • Dimensions (W x H x D): 67.1 x 28.2 x 67.1 mm • Weight: approx 100 g • Shipping carton dimensions (W x H x D): 100 x 60 x 80 mm • Shipping carton weight: approx 200 g • 28-Pin, High-Performance, Enhanced Flash, USB 2.0 Microcontroller with nanoWatt Technology • Single chip USB to asynchronous serial data transfer interface • USB 2.0 Full Speed compatible • Low USB bandwidth consumption • Operating Temperature: 0 °C to 50 °C • Operating Voltage Range: 3.3 V to 5.25 V • High-Current Sink/Source: 25 mA/25 mA • 100,000 Erase/Write Cycle Enhanced Flash Program Memory Typical for firmware updates • Flash/Data EEPROM Retention: > 40 Years • 16 Digital +5 V TTL Lines o 8 TTL Input o 8 TTL Output • Accessed via standard Virtual COM Port (VCP) • TTL Input Lines configured as an 8 bit port • TTL Output Lines configured as an 8 bit port • Change detection on TTL Input Lines • TTL Input to 2 hex bytes conversion representing 255 possible states • 2 hex bytes to TTL output across 8 bit port representing 255 possible states • Custom designed firmware o Checks for a TTL event mark or trigger event 109,000 times a second (109 kHz sampling rate) o Typical time to send a TTL output or event mark from a two byte hex code from the PC, 254 µs# o Typical time to respond to a TTL input/trigger pulse or sync signal and send a two byte hex code to the PC, 350 µs# o Typical time for 50 TTL outputs or event marking pairs (on|off), M = 290 µs, SD = 10 µs, measured using our configuration and latency validation software for Microsoft Windows (Win 7 64 SP1, USB 2) and modules internal hardware timer# o Supplied with configuration and latency validation software for Windows XP, Vista, Win 7, Win 8/8.1 and Win 10 o Built-in hardware timing checks based on elapsed time between two sequential event marks #Dependent on specific USB subsystem and using the USB TTL Configuration utility to check correct for correct installation. • Moulded grey ABS plastic enclosure • Stainless Steel front and rear panels with DP1 finish • Custom designed PCB o Material: FR4 o Solder Resist Coating: CAWN_1331 green resist and CAWN_1291 green hardener • Lead free solder: MULTICORE / LOCTITE - 96SC 400 5C 1.00MM - SOLDER WIRE (Henkel 60EN 362 5C) 6.2 Timing Specifications • • • • • • Checks for a TTL event mark or trigger event 109,000 times a second (109 kHz sampling rate) Typical time to send a TTL output or event mark from a two byte hex code from the PC, 254 µs# Typical time to respond to a TTL input/trigger pulse or sync signal and send a two byte hex code to the PC, 350 µs# Typical time for 50 TTL outputs or event marking pairs (on|off), M = 290 µs, SD = 10 µs, measured using our configuration and latency validation software for Microsoft Windows (Win 7 64 SP1, USB 2) and modules internal hardware timer# Supplied with configuration and latency validation software for Windows XP, Vista, Win 7, Win 8/8.1 and Win 10 Built-in hardware timing checks based on elapsed time between two sequential event marks #Dependent on specific USB subsystem and using the USB TTL Configuration utility to check correct for correct installation. Typical time to send a TTL output or event mark (orange) from a two byte hex code from the PC (blue) TTL sampling rate, i.e. how many times a second TTL I/O status is checked Typical time for 50 TTL outputs or event marking pairs (on|off) measured using our configuration and latency validation software for Microsoft Windows (Win 7 64 SP1, USB 2) Typical time to respond to a TTL input/trigger pulse or sync signal (orange) and send a two byte hex code to the PC (blue)