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What kind of operating environment does the BASIC Stamp Microcontroller Require?

The BASIC Stamp modules are designed to function in at least 0° to 70° C temperatures with up to 70%, non-condensing humidity. While the modules may continue to function outside these ranges, it is not guaranteed or recommended. Additionally, it is best to keep the BASIC Stamp modules away from, or shielded from, any nearby RF interference as this may impact the accuracy of its I/O functions.

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What are the main differences between the BASIC Stamp modules?

The BASIC Stamp 1 module has 8 I/O pins, 14 bytes of available RAM, room for approximately 80 lines of code, executes approximately 2000 instructions per second and requires a serial interface and adapter for programming.

The BASIC Stamp 2 module has 16 I/O pins, 26 bytes of available RAM, 2 dedicated serial port pins (1 input, 1 output), room for approximately 500 lines of code, executes approximately 4000 instructions per second and requires a serial interface for programming. The BASIC Stamp 2e module has 16 I/O pins, 26 bytes of available RAM, 64 bytes of Scratch Pad RAM, 2 dedicated serial port pins (1 input, 1 output), room for approximately 4000 lines of code, executes approximately 4000 instructions per second and requires a serial interface for programming. The BASIC Stamp 2sx module has 16 I/O pins, 26 bytes of available RAM, 64 bytes of Scratch Pad RAM, 2 dedicated serial port pins (1 input, 1 output), room for approximately 4000 lines of code, executes approximately 10000 instructions per second and requires a serial interface for programming. The BASIC Stamp 2p24 module has 16 I/O pins, 26 bytes of available RAM, 128 bytes of Scratch Pad RAM, 2 dedicated serial port pins (1 input, 1 output), room for approximately 4000 lines of code, executes approximately 12000 instructions per second and requires a serial interface for programming. The BASIC Stamp 2p40 module has 16 I/O pins, 26 bytes of available RAM, 128 bytes of Scratch Pad RAM, 2 dedicated serial port pins (1 input, 1 output), room for approximately 4000 lines of code, executes approximately 12000 instructions per second and requires a serial interface for programming. The BASIC Stamp 2pe module has 16 I/O pins, 26 bytes of available RAM, 128 bytes of Scratch Pad RAM, 2 dedicated serial port pins (1 input, 1 output), room for approximately 4000 lines of code, executes approximately 6000 instructions per second and requires a serial interface for programming. The BASIC Stamp 2px24 module has 16 I/O pins, 26 bytes of available RAM, 128 bytes of Scratch Pad RAM, 2 dedicated serial port pins (1 input, 1 output), room for approximately 4000 lines of code, executes approximately 19000 instructions per second and requires a serial interface for programming.

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Is the BASIC Stamp 2 better then the BASIC Stamp 1 module?

Yes and no, depending on your application. The BASIC Stamp modules from the BASIC Stamp 2 module to the BASIC Stamp 2px module have twice the number of I/O pins with the exception of the BS2p40 which has 32 I/O pins, more than twice the execution speed, more than 5 times the memory (code) space, a serial port and approximately 5 times the resolution on time sensitive commands. In many cases, these BASIC Stamp microcontrollers fit our customer's applications better than the BASIC Stamp 1 module. In some cases, however, this is not true. For example, you may have a need for only a couple of inputs and outputs with which you need to perform relatively simple, non speed-critical tasks. This is a perfect application for the BASIC Stamp 1 module; the BASIC Stamp 2 module on up would be overkill if used in this way. A slightly different example would be if you have a variable pulse width signal you need to monitor. The BASIC Stamp 1 module can detect and measure a pulse as little as 10 µS wide and as long as 0.65535 seconds wide. The BASIC Stamp 2 module and above has 5 times the resolution, so it can measure a pulse as little as 2 µS wide, however, only as long as 0.13107 seconds wide of course with the faster Stamps the pulse width would vary you may want to refer to the BASIC Stamp Manual Version 2.0 off of our website, you will the information in the PULSIN command. While the better resolution may be helpful, the smaller maximum pulse width measuring capability may prove disadvantageous to your application. The BASIC Stamp 2 module series is the most popular BASIC Stamp microcontroller and has the widest support base of free material on the web and from Parallax.

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Is the BASIC Stamp 2sx better then the BASIC Stamp 2 module?

Yes and no, depending on your application. The BASIC Stamp 2sx module executes instructions 2.5 times as fast, has 8 times the memory (code) space and 2.5 times the resolution on time sensitive commands. In some cases, the BASIC Stamp 2sx module fits applications better than the BASIC Stamp 2 module. For example, you may have a need for additional program space that doesn’t exist in the Stamp 2. Another example would be if you have a variable pulse width signal you need to monitor. The BASIC Stamp 2 module can detect and measure a pulse as little as 2 µS wide and as long as 0.13107 seconds wide. The BASIC Stamp 2sx module has 2.5 times the resolution, so it can measure a pulse as little as 800 nS wide, however, only as long as 0.05243 seconds wide. While the better resolution may be helpful, the smaller maximum pulse width measuring capability may prove disadvantageous to your application.

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How many I/O pins does the BASIC Stamp microcontroller have?

The BASIC Stamp 1 module has 8 I/O pins while the BASIC Stamp 2 module, BASIC Stamp 2e module, BASIC Stamp 2sx module, BASIC Stamp 2p24 module, BASIC Stamp 2pe, and the BASIC Stamp 2px24 module have 16 I/O pins plus 2 special serial port pins (1 input, 1 output) the BASIC Stamp 2p40 module has 32 I/O pins plus 2 special serial port pins (1 input, 1 output).

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What can I use the I/O pins for?

The BASIC Stamp microcontroller’s I/O pins are perfectly suited for digital input and output with TTL/CMOS level (0 to 5 volt) signals. However, you can use some special commands and techniques to input and output limited analog signals. For example, the RCTIME and PWM commands can be used to read a variable resistance or output a variable voltage from 0 to 5 volts. The I/O pins can not be used to read analog voltages by themselves, however, but this can be done by interfacing the I/O pins to an A to D converter chip.

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Can the I/O pins be used to control relays, solenoids and other similar devices?

Yes, however, due to the demanding current and voltage requirements of some of these components, driver circuitry will need to be used to properly isolate the I/O pins from harmful effects. For examples of this, refer to BASIC Stamp 1 module Application Note #6 and BASIC Stamp Article #6, “Silicon Steroids for Stamps”.

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Can I control LEDs with the I/O pins?

Yes. Simply use a 470 ohm resistor in series with the LED to limit the current draw through the I/O pin (see “How much current can the I/O pins handle?”). Also, keep in mind that most LEDs require a lot of current in relation to what the BASIC Stamp microcontroller can provide. If you attach and power 3 or more LEDs at one time from the BASIC Stamp module’s I/O pins, you are likely to see flaky and unpredictable results caused by voltage sag, I/O pin damage and/or hardware resets. Driver circuitry or low current LEDs will need to be used if you require such an application.

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How much current can the I/O pins handle?

On the BASIC Stamp 1 module and BASIC Stamp 2 module, each I/O pin is capable of sourcing 20mA and sinking 25mA. The total across each group of 8 I/O pins should not exceed 40mA source or 50mA sink. On the BS2e, BS2sx, BS2p24, BS2p40, BS2pe and BS2px24, each I/O pin is capable of sourcing and sinking 30mA. The total current draw across each group of 8 I/O pins should not exceed 60mA.

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What is the input impedance of the BASIC Stamp module's I/O pins?

Approximately 1 Meg Ohm.

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How fast does the BASIC Stamp microcontroller execute its PBASIC code?

On average, the BASIC Stamp 1 module executes approximately 2,000 instructions per second, the BASIC Stamp 2 module executes approximately 4,000 instructions per second, the BASIC Stamp 2e module executes approximately 4,000 instructions per second, the BASIC Stamp 2sx module executes approximately 10,000 instructions per second, the BASIC Stamp 2p24 module executes approximately 12,000 instructions per second, the BASIC Stamp 2p40 module executes approximately 12,000 instructions per second, the BASIC Stamp 2pe module executes approximately 6,000 instructions per second and the BASIC Stamp 2px24 module executes approximately 19,000 instructions per second. The true execution speed depends upon many factors including, the particular set of instructions used and the type of arguments provided to the instructions. Some instructions execute at a much faster rate while others, especially those that have to deal with external signal measurement or specific protocol speeds, will execute much slower.

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What is the VIN pin used for?

The Vin (Voltage Input) pin is used to power the Stamps from a voltage source higher than 5 volts. The voltage on the Vin pin should be between 5.5 to 15 volts for the BASIC Stamp 1 module and the BASIC Stamp 2 module. The voltage on the Vin pin should be between 5.5 to 12 volts for the BASIC Stamp 2e module, the BASIC Stamp 2sx module, the BASIC Stamp 2p24 module, the BASIC Stamp 2p40 module, the BASIC Stamp 2pe module and the BASIC Stamp 2px24 module. The Vin pin is the positive connection while the Vss pin is the negative, or ground, connection. When powered from the Vin pin the Stamp regulates the voltage down and outputs +5 volts on the Vdd pin. For optimal operation, it is recommended to keep the voltage below 12 volts for the BASIC Stamp 1 and 2 modules, and around 7.5 volts for the BASIC Stamp 2e module, BASIC Stamp 2sx module, BASIC Stamp 2p24 module, BASIC Stamp 2p40 module, BASIC Stamp 2pe module and BASIC Stamp 2px24 module.

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How does the VDD pin work?

The Vdd pin (+5V) outputs 5 volts when the Stamp is powered by an external source using the Vin and Vss (ground) pins. The voltage on the Vin pin should be between 5.5 to 15 volts for the BASIC Stamp 1 module and the BASIC Stamp 2 module. The voltage on the Vin pin should be between 5.5 to 12 volts for the BASIC Stamp 2e module, the BASIC Stamp 2sx module, the BASIC Stamp 2p24 module, the BASIC Stamp 2p40 module, the BASIC Stamp 2pe module and the BASIC Stamp 2px24 module. The Vdd pin can be used to power other circuitry if the overall current consumption is within the capabilities of the Stamp’s regulator. The Vdd pin can also be used to power the Stamp from an external 5-volt regulator. In this case, the Vdd pin must be connected to +5 volts output of the regulator and the Vss (ground) pin is the negative connection of the regulator (leave Vin disconnected).

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How does the reset pin (RES) work?

The reset pin is internally controlled by the Stamp’s brownout detector. It is normally high (+5V), which allows the Stamp to run its program normally, and is pulled low when the power supply voltage drops below 4.2 volts (safely putting the Stamp to sleep). This pin can be monitored to detect when a reset condition occurs, or, you can pull the line to ground to force a reset. After the reset pin is allowed to rise to +5 volts, the Stamp 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 the Stamp to run normally. This pin has an inverse relationship to the ATN (Attention) pin on the BASIC Stamp 2 module, BASIC STAMP 2e module, BASIC Stamp 2sx module, BASIC Stamp 2p24 module, BASIC Stamp 2p40 module, BASIC Stamp 2pe module, and BASIC Stamp 2px24 module.

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How does the ATN (Attention) pin work (BASIC Stamp 2 family of modules)?

The ATN pin is used strictly for programming the BASIC Stamp microcontroller and should not be connected to anything other than the DTR pin of the programming connector and/or filtering capacitors. The ATN pin is an input and has an inverse relationship with the reset (RES) pin. >When the ATN pin is left unconnected, or is driven low, it causes the RES pin to go high. When the ATN pin is driven high it causes the RES pin to go low (performing a hardware reset on the BASIC Stamp microcontroller). The BASIC Stamp editor software toggles this pin from low to high and then low again at the start of the programming process to perform a hardware reset on the module and begin the bi-directional programming communication. It is important to be aware of a particular artifact of the DTR pin on a standard serial port: upon port selection by standard software (terminal packages, development tools, etc.), the DTR pin is driven high by default. If the same connections for programming the BASIC Stamp module are used to communicate with it via a serial port, the default state of the DTR pin will cause the BASIC Stamp module to be held in permanent reset and its program will not execute.

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How much current can the BASIC Stamp microcontroller's on-board regulator provide?

The built in 5-volt regulator on the BASIC Stamp 1 module and BASIC Stamp 2 module can supply 50mA of current if powered by a 12-volt source. The BASIC Stamp 1 module consumes 1mA leaving 49mA available to power external devices not including any devices connected to the I/O pins. The BASIC Stamp 2 module consumes 3mA of current leaving 47mA available to power external devices not including any devices connected to the I/O pins. The BASIC Stamp 2e, BASIC Stamp 2sx, BASIC Stamp 2p24, BASIC Stamp 2p40, BASIC Stamp 2pe and BASIC Stamp 2px24 module regulators can supply 150mA if powered by a 7.5-volt source. The BASIC Stamp 2e module consumes 25mA. This leaves 125mA for use with other circuitry via the VDD pin and the I/O pins. The BASIC Stamp 2sx module consumes 60mA. This leaves 90mA for use with other circuitry via the VDD pin and the I/O pins. The BASIC Stamp 2p24 module consumes 40mA. This leaves 110mA for use with other circuitry via the VDD pin and the I/O pins. The BASIC Stamp 2p40 module consumes 40mA. This leaves 110mA for use with other circuitry via the VDD pin and the I/O pins. The BASIC Stamp 2pe module consumes 15mA. This leaves 135mA for use with other circuitry via the VDD pin and the I/O pins. The BASIC Stamp 2px24 module consumes 55mA. This leaves 95mA for use with other circuitry via the VDD pin and the I/O pins.

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Can the BASIC Stamp microcontroller generate a sine wave?

Only the BASIC Stamp 2 module, BASIC Stamp 2e, BASIC Stamp 2sx module, BASIC Stamp 2p24 module, BASIC Stamp 2p40 module, BASIC Stamp 2pe module, and BASIC Stamp 2px24 module can generate sine waves. The BASIC Stamp 2 and 2e modules use the FREQOUT command to generate from 0 Hz to 32,767 Hz. The BASIC Stamp 2sx module uses the FREQOUT command to generate from 0 Hz to 81,917 Hz. The BASIC Stamp 2p24 and p40 modules use the FREQOUT command to generate from 0 Hz to 123,531 Hz. The BASIC Stamp 2pe module uses the FREQOUT command to generate from 0 Hz to 49,478 Hz. The BASIC Stamp 2px24 module uses the FREQOUT command to generate from 0 Hz to 197,585 Hz. Note that the output from the FREQOUT command appears to be static when viewed on an oscilloscope. This is due to the nature of the underlying algorithm that generates the frequency, however, when averaged out over time, the result is a sine wave. You may achieve a cleaner signal by attaching the I/O pin to an appropriate RC filter circuit.

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Can the BASIC Stamp microcontroller generate a sine wave on two pins at once?

No. The BASIC Stamp module is a single-task device and thus will execute only one FREQOUT command at a time.

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Can the BASIC Stamp module generate more than one sine wave on a pin at the same time?

Yes, the BASIC Stamp 2, 2e, 2sx, 2p24, 2p40, 2pe, and 2px24 modules FREQOUT command can generate two frequencies at the same time, on the same pin. This can be used to create harmonics, which greatly improve the sound output.

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Can the BASIC Stamp microcontroller generate square waves?

Yes, however, it is limited. The SOUND command in the BASIC Stamp 1 module generates square waves which vary from 94.8 Hz to 10,550 Hz (non-linearly). The BASIC Stamp 2, 2e, 2sx, 2p24, 2p40, 2pe and 2px24 modules however, do not include any functions to generate an accurately timed square wave. It can be done manually as long as fast timing is not an issue. This can be done with multiple lines of code that simply set a pin high or low and pause for the appropriate duration in-between transitions. The timing will vary somewhat depending upon your loop execution speeds.

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Does the BASIC Stamp microcontroller include a real time clock function?

No. If you need to keep track of time, especially the date and time, it is best to interface a real time clock to the BASIC Stamp modules. Many are available from various manufacturers. The real time clocks with a serial interface are usually the best choice, as they require fewer I/O pins from the BASIC Stamp modules to function properly. Parallax sells the DS1302 chip in the Component Shop to address this issue.

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Does the BASIC Stamp module have a built in timer?

Yes, however, it is used for timing functions within the BASIC Stamp microcontroller’s interpreter and there is no direct access to it through any PBASIC commands. Refer to BASIC Stamp 1 module Application Note #20, “An Accurate Time base” for one possible solution to timing problems. Please refer to the application notes on our website.

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Does the BASIC Stamp module support interrupts?

No, the interpreter chip used in the BASIC Stamp microcontroller does not support interrupts. In many cases, a fast polling routine may be used to accomplish the same effect, however, depending on the number and size of the tasks involved in some applications, this will not be fast enough and the BASIC Stamp microcontroller may not be a plausible solution. While not true interrupts, the BS2p24, BS2p40 and BS2px24 modules support “polled interrupts.” The “polling” commands allow the BASIC Stamp modules to respond to certain I/O pin events at a faster rate than what is normally possible through manual PBASIC programming. In this case the interpreter periodically checks the state of the designated polled-input pins. It “polls” these pins after the end of each PBASIC command and before it reads the next PBASIC command from the user program; giving the appearance that it is polling “in the background.”

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Is there a way a customer can update Stamp code without having my source code?

Yes, on the latest editor version, you can find it under, File/Generate Object code. You can generate object code, object code with stamp loader or a stand-alone executable. This will allow you to give a customer updates to your code without having the source.

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