MicroStamp11 Frequently Asked Questions
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1. It can also be used to implement a time of day clock calendar The increments for a Turbo MicroStamp1 1 are 3 333 ms 6 667 ms 13 33 ms and 26 67 ms Does MicroStamp11 support interrupts Yes there are 20 different interrupt sources on MicroStamp11 These are all user enabled so that an interrupt can be made to occur on such events as an input pin logic level changes the hardware timer overflows the hardware free running counter matches a user defined value a byte has been received via the serial port There are also two interrupt input pins IRQ and XIRQ which can be used to signal MicroStamp11 when some external event has occurred Additionally any of the interrupts can be used to trigger a wake up of MicroStamp11 from sleep mode This is a very important advantage that MicroStamp11 has over similarly priced stamp sized modules Questions regarding operation and use How do I program MicroStamp11 You can write your BASIC C or assembler program using any text editor eg Notepad or Edit on a standard IBM compatible PC After you compile and assemble the code for your application you simply plug MicroStamp11 into a Docking Modle connect the Docking Module to the computer s serial port provide power to the Docking Module slide both switches to LOAD and press the reset button To download your program into MicroStamp11 s EEPROM use the DOS batchfile included with the Starter Package or the new Windows SmartLoad12. application circuits and attach the ribbon cable between the adapter and the Docking Module When you are finished and no longer need the Docking Module remove the ribbon cable from the adapter and substitute MicroStamp1 1 The right angle dual row receptacle connector option FRA provided on the module can be used with any commonly available 20 pin dual row male connector having 025 square pins In fact a couple are included in the Starter Package for your convenience How big a program can I store in MicroStamp11 MicroStamp11 has 8K or 32K bytes of program storage depending on which version you purchased Most MCU instructions require from to 3 bytes of storage space This means you have enough space for about 11 000 instructions on a 32K version or 2 730 instructions on an 8K version If you re writing your code in C or BASIC the number of lines of code you can store will depend on the number of instructions it takes the compiler to implement a line of code This number will vary greatly depending on the line of code being compiled Can I expand the program memory Not directly however you can add non volatile memory EEPROM or Flash via the SPI port for archiving programs or subroutines and then have your main program load them into RAM whenever you wish to execute them Can I expand the data memory MicroStamp1 1 is now available in a MAX version which adds 32K bytes of data memory by means of a RAM chip stacked on top
3. pins 12 and 11 on MicroStamp11 How much current does MicroStamp11 draw MicroStamp11 consumes approximately 15 mA in running mode and 20 uA in sleep mode not including any circuitry on the I O pins Is MicroStamp11 sensitive to static electricity While many electronic devices including MicroStamp11 can be damaged by static electricity MicroStamp11 is generally more tolerant of static We do however recommend taking all the usual precautions when handling MicroStamp1 1s in static prone environments Can MicroStamp11 be embedded into my product for volume manufacturing Yes Technological Arts offers MicroStamp11 modules in volume at a discounted price for economical integra tion into your products A variety of connector options is offered to suit your needs What items do I need to get started with MicroStamp11 he items you need are 1 programming software to develop your application 2 Docking Module with serial cable 3 MicroStamp11 module 4 program which loads your application into MicroStamp1 1 s memory 5 a ribbon cable breadboard adapter assembly 6 manual If you are new to MicroStamp11 it is best to purchase a MicroStamp11 Starter Package This package includes all six of the items listed above at a lower cost than if you were to purchase them separately What kind of microcontroller chip is used in MicroStamp11 MicroStamp11 uses an MC68HC11D0 a high performance CMOS chip made by Motorola What kind of environm
4. should not exceed 80 mA source or sink at any given time Can MicroStamp11 generate analog voltages Generating an analog output is very simple using a PWM waveform in conjunction with a resistor and capacitor Alternatively a DAC can be added via the SPI port see below What can I use the SPI pins for The Serial Peripheral Interface SPI pronounced spy opens up a whole realm of possibilities for I O expansion Some possibilities are multi channel analog to digital conversion non volatile data storage serial EEPROM real time clock calendar functions LCD interface and a virtually unlimited number of additional input and output lines How fast does MicroStamp11 execute code The MCU in atandard MicroStamp11 has a bus speed of 2MHz This translates to an instruction cycle time of 500ns Most 68HC11 instructions execute in 2 to 9 cycles with an average of around 4 cycles This means MicroStamp11 can execute code at an average speed of 500 000 instructions per second 0 5 MIPS The true execution speed depends upon many factors including the particular set of instructions used and their addressing modes A Turbo version of MicroStamp11 operating at 9 8304 M Hz is now available This gives a 23 speed increase What is the Vin pin used for The Vin Voltage input pin is used to power MicroStamp11 from a 6 to 15 Volt source The Vin pin is the positive connection while the GROUND pin is the negative or ground connection When
5. 1 available soon As soon as the program has been downloaded successfully slide the switches back to RUN and PROT press the reset button and MicroStamp11 begins executing its new program starting at the first line of code How does my program get stored in MicroStamp11 Your code gets stored within MicroStamp11 s EEPROM memory This memory is non volatile meaning it retains its program even without power Every time MicroStamp11 receives power or is reset it starts running code directly out of EEPROM starting with the first executable line Source code elements like comments and constant and variable names are not stored in MicroStamp11 thus you may feel free to use as many comments and descriptive symbol names in your code as you like without worrying about increasing your code size How do I erase MicroStamp11 s program space An erase cycle is performed automatically on every byte that is to be changed so erasing is not necessary Addresses which do not need to be changed are not erased How do I re program MicroStamp11 Simply re connect it to the computer via the Docking Module and run the MicroStamp11 DOS batchfile or Windows SmartLoad11 The standard configuration of the Starter Package includes a ribbon cable and solderless breadboard adapter so you can leave MicroStamp11 in the Docking Module while you re developing your application Just plug the adapter into your solderless breadboard in place of MicroStamp11 Wire up your
6. C programming language which many people are familiar with It is a Freeware compiler written by Karl Lunt and is intended for educational and personal use It is not permitted to be used for the development of commercial applications SBASIC has special commands to efficiently control the features of the 68HC11 MCU Can I embed assembly language routines in my SBASIC or C code Yes SBASIC and C are both compilers not interpreters and they allow assembly language routines to be included wherever desired You run the compiler on the completed program to produce assembly language code Then you assemble it to produce a downloadable file called an s record How do I know how much space my program consumes A quick estimate can be made by dividing the s19 filesize by two But the best way is to look at the listing file generated by the assembler to see what is the last address it put code in How do I debug my programs There are two kinds of errors arising in programs 1 Syntax errors missing or incorrect punctuation and misspelled keywords for example 2 Logical errors faulty logic where the resulting flow control is not what was desired for example Syntax errors can be corrected by examining the offending line s and comparing them with the definitions provided in the compiler user manual Logical errors are sometimes more difficult to find but may be more easily discovered by careful placement of print commands For example you can pri
7. Technological MicroStamp11 Frequently Asked Questions What is MicroStamp11 MicroStamp11 is a tiny microcontroller module which can be programmed using BASIC C assembler Forth or Pascal programming language or any other language available for the 68HC11 It is about the size of a commemorative postage stamp hence it was dubbed stamp How does MicroStamp11 compare with the BASIC Stamp There are many fundamental differences See comparison chart for details http support technologicalarts ca docs MicroStamp11 BS2vsMS11 html Does MicroStamp11 lose its program when I disconnect the battery or power supply No your code is stored inside an EEPROM on board MicroStamp11 EEPROMs provide non volatile storage they retain memory even without power The EEPROM used in MicroStamp11 is guaranteed to function properly for at least 10 years and for 1 000 000 write cycles per memory location How big is MicroStamp11 MicroStamp11 measures 1 4 36 mm L x 1 0 25 mm W x 0 4 10 mm H excluding the connector How do I power MicroStamp11 MicroStamp11 runs on 5 to 15 Volts DC It features an on board 5 Volt regulator which converts the input 6 to 15 Volts on the Vin pin to the 5 Volts that its components require If your power supply is 6 to 15 Volts you should connect it directly to the VIN and GND pins 10 and 11 on MicroStamp11 If your power supply delivers a regulated 5 Volts you should connect it directly to the 5V and GND
8. corruption due to power glitches During programming slide the switch to the LOAD position After the code has been loaded slide both switches away from the LOAD position ie to RUN and PROT Reset the board to cause the MCU to begin executing your program How much current can MicroStamp11 s on board regulator provide The 5 Volt regulator built into MicroStamp11 can supply 100 mA current if powered by a 6 Volt source The limit is affected by operating temperature so if the unit is running significantly above room temperature the maximum current it can supply will be reduced The amount it can supply will also be reduced if you use a higher input voltage This is because the regulator drops the voltage to 5 Volts by dissipating the excess voltage as heat MicroStamp11 draws approximately 15 mA in RUN mode leaving 85 mA for use with other circuitry via the 5VDC pin and the I O pins Can MicroStamp11 generate a sine wave Yes MicroStamp11 can be made to generate a sine wave by means of a continually varying pulse width on an output pin By adding an RC circuit to average out the PWM waveform over time the result is a sine wave The same technique can be used to generate other types of waveforms as well Can MicroStamp11 generate a waveform on two pins at once Yes MicroStamp11 is a multi tasking device utilizing a hardware timer system and interrupts to generate waveforms independently and thus can generate more than one waveform at a ti
9. ent can MicroStamp11 operate in MicroStamp11 modules will work over a temperature range of 0 to 70 C with up to 70 non condensing humidity While the modules may continue to function outside these ranges it is not guaranteed or recommended by Technological Arts Additionally it is best to keep MicroStamp11 modules away from or shielded from any nearby RF interference as this may impact the accuracy of the I O functions How many I O pins does MicroStamp11 have MicroStamp11 has 14 multi purpose I O pins plus 2 hardware interrupt pins What can I use the I O pins for MicroStamp11 s I O pins are perfectly suited to digital input and output with TTL CMOS level 0 to 5 Volt signals In addition to basic I O all of the pins have alternate functions related to a powerful set of on chip hardware subsystems These subsystems include SCI SPI 16 bit timer counter and RTI Can the I O pins be used to control relays solenoids motors and other similar devices Yes however due to the demanding current and voltage requirements of some of these components driver circuitry will be required in order to properly isolate the I O pins from harmful effects Can I control LEDs with the I O pins Yes Simply use a 330 ohm resistor in series with the LED to limit the current draw through the I O pin How much current can the I O pins handle Each I O pin is capable of sourcing or sinking a maximum of 25 mA however the total across all I O pins
10. me besides doing other tasks Can MicroStamp11 generate square waves Yes it is very easy to do this using the Output Compare feature of the hardware timer subsystem Can MicroStamp11 generate vary the pulse width of a square wave The duty cycle of the square wave can easily be varied to produce a PWM waveform Varying the pulse width can for example control the shaft position of a servo motor the speed of a DC motor the effective brightness of a light or the temperature of a heater Does MicroStamp11 include a real time clock function Not exactly However it does have a real time interrupt RTI which can be used to accurately measure the passage of time In fact a Turbo MicroStamp11 s RTI rate is exactly 3 3333 ms making it easy to keep track of time accurately to 1 100th of a second ie Every 3 interrupts equals 10 ms If you are not using the Turbo version or if you need to keep track of absolute time especially dates and time it is best to interface a real time clock calendar chip to MicroStamp11 Many are available from various manufacturers Those with a serial interface are usually the best choice as they can be implemented with fewer MicroStamp11 I O pins Does MicroStamp11 have a built in timer Yes it has a real time interrupt that is programmable in increments of 4 096 ms 8 192 ms 16 384 ms or 32 768 ms This can be used for such applications as task scheduling switch debouncing or elapsed time measurement
11. nt the current status of specific variables in your program to the serial port as it is executed Then monitor the serial port using any terminal program Can I read out the program which is already stored in MicroStamp11 Yes using PCBug11 you can examine and modify the contents of MicroStamp11 s EEPROM as well as RAM and the MCU registers You can also disassemble it displaying the contents in assembly language However there is no way to reassemble it into the original C or BASIC program Can my program store sensor values to the on board EEPROM ie datalogging No on board EEPROM is reserved for your program and any constant data eg text messages conversion factors etc After programming you switch the WRITE PROT switch on preventing EEPROM from being written to To log data values eg sensor values you should store them in serial EEPROM or serial Flash that you interface to the SPI port
12. of the EEPROM 32K version only This is ideal for larger applications which require more variables greater stack space and structures sucha as arrays Whether you have a MAX or standard MicroStamp11 you can still interface serial EEPROMs or other memory devices via MicroStamp11 s I O pins eg SPI to gain more data storage area You will have to include the appropriate code within your program to interface to the particular device you choose How difficult is it to program MicroStamp11 When compared to other programmable microcontrollers MicroStamp11 is perhaps the easiest to use because of its powerful hardware subsystems the variety of languages supported and its straightforward method of downloading and debugging If you have some experience programming in BASIC C or Pascal you should find the learning process with MicroStamp11 to be a fairly simple one once you get to know the MCU s hardware features If however you have never had any programming experience you may have to spend some extra time studying the examples and application notes provided before you feel comfortable with MicroStamp11 Can I program MicroStamp11 in Visual BASIC TurboPascal or QBASIC No These languages produce programs that are meant to be executed ona PC MicroStamp11 is a microcontrol ler not a miniature PC It does not have a graphical user interface a hard drive or a lot of memory What is SBASIC SBASIC is a 68HC11 specific form of the BASI
13. powered from the Vin pin MicroStamp11 regulates the voltage down and outputs 5 Volts on the 5VDC pin How does the 5VDC pin work The 5VDC pin pin 12 outputs 5 Volts when MicroStamp11 is powered by a 6 to 15 Volt source using the Vin and GROUND pin 11 pins The 5VDC pin can be used to power other circuitry provided that the overall current consumption is within the capabilities of MicroStamp11 s regulator How does the reset pin RESET work The reset pin is internally controlled by MicroStamp11 s low voltage inhibit circuit It is normally high 5V which allows MicroStamp11 to run its program and is pulled low when the power supply voltage drops below 4 Volts which safely puts MicroStamp11 in a reset state This pin can be monitored to detect when a reset condition occurs or you can pull the line to ground to force a reset via the reset button on the Docking Module for example After the reset pin is allowed to rise to 5 Volts MicroStamp11 wakes up and starts executing its program from the first line of code Do not drive this pin high it should be left electrically disconnected floating when you want MicroStamp11 to run normally What are the slide switches for During programming the MCU needs to be put in a Special Bootstrap Mode so that the program can be loaded in via the serial port This position is labelled LOAD on the RUN LOAD switch SW2 The other switch SW3 is for protecting the contents of EEPROM from
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