The QuickStart is an evaluation board for the Propeller microcontroller. As an open-source reference design, the QuickStart board provides basic Propeller circuitry. Developers may use PCB layout files as their own to speed their project toward completion. As a project board, the QuickStart is fully expandable and provides unimpeded access to all I/O pins through an expansion header, but also includes some button inputs and LEDs to demonstrate programming. With USB power and a selection of QuickStart Project examples, it's also the fastest way to get up and running.
Propeller QuickStart Board Features
- Open hardware reference design through Altium and DipTrace PCB layout files
- Propeller P8X32A microcontroller
- Bus-powered USB coupled with 3.3V regulator for 500 mA
- 5 MHz cyrstal on board may be disabled by removing SMT jumper, allowing replacement with external through-hole crystal
- 64KB EEPROM (32K for P8X32A program; 32K for general-purpose use)
- External brownout reset may be installed by removing SMT jumper
- Eight blue LEDs on P16-P23
- Eight resistive touch-buttons on P0-P7
- Pads for sigma-delta A/D circuitry (two resistors and two capacitors, both 0603) for using the Sigma-Delta A/D AppNote
- Expansion header provides access to Vss, Vdd, 32 I/O pins (28 for any use, two are I2C bus, and two are optional Tx/Rx if connected to USB power)
- Power Requirements: 3.3V or 4V to 9V DC, up to 500 mA
- Communication Interface: USB, 3.3V serial, I2C
- Operating temperature: -40 to +185 °F (-40 to +85 °C)
- Dimensions: 2" × 3" × 0.36" (5.1 cm × 7.6 cm × 0.84 cm)
Operating Specifications and Maximums
|Symbol ||Parameter ||Abs. |
|Min. ||Typ. ||Max. ||Abs. |
|Vin||Supply Voltage on J1 pin 40||-0.3V||4.0V||5.0V||9.0V||18.0V |
|Vdd||Supply Voltage on J1 pin 38||-0.3V||3.0V||3.3V||3.6V||4.0V |
Setup & Programming Setup is fast and easy; just follow the QuickStart Examples below. Before connecting your board to your computer, download and install a Propeller programming environment and FTDI drivers — your choices are described in QuickStart 1. You will need a USB-A to Mini-B cable.
P8X32A QuickStart Board Specifications
Parallax P8X32A Propeller Microcontroller
The Propeller microcontroller, U1, is an 8-core low-power microcontroller with 32 KB SRAM and up to 20 MIPS per core. By partitioning separate tasks into separate cores, the Propeller can load programs and features and can reallocate resources on the fly, without the overhead of an operating system. Features that often require dedicated hardware can be defined in software and run in parallel. When running at a total of 160 MIPS, the power consumption is usually less than 80 mA. For more information, refer to the Propeller P8X32A datasheet.
The USB mini B port, J2, connects to an FTDI FT232RL USB-to-serial converter, U3. The I/O pins from U3 are buffered through U4. The TXD pin from U3 connects to RX, or P31, on the Propeller. The RXD pin from U3 connects to TX, or P30, on the Propeller. The USB circuitry, including U3 and U4, is powered from the USB bus, so when there is no USB connection present, the unpowered buffer's inputs and outputs will float, leaving P30 and P31 available for other uses, such as programming the Propeller from an external device.
The power LED, D11, will light green with sufficient power on Vdd. It may also light or partially light with insufficient power on Vdd.
D1 through D8 indicate the status of P0 through P7, respectively. The LEDs are driven through a buffer, so they do not load the I/O pins. If the P0 through P7 are left floating, the LEDs may light when the respective I/O pin floats high. To ensure that they stay off when the I/O pin is not in use, drive the I/O pin low.
Resistive Touch Buttons
P0 through P7 are connected to resistive touch buttons. Each button is a pad, surrounded by ground pads, connected through a 100 K Ohm ESD protection resistor, to the I/O pin. When the buttons are not in use, they will not load the I/O pins. When touched, they will add negligible resistive loading. To read the state of the button, set the I/O pin as a high output, then immediately switch it to an input, then measure the amount of time before the I/O pin falls low. If nothing is touching the pad, the parasitic capacitance of the I/O pin and the PCB will hold the input high for several milliseconds. Alternatively, instead of measuring the fall time, measure the input state 1 millisecond after the pin was switched to an input. See the "Touch Buttons LED Demo" from the Resources section below.
The 64KB EEPROM is connected to the I2C bus on P27 and P28. The lower 32KB contain the program that the Propeller loads on reset. The upper 32KB should be used for non-volatile data storage, such as network settings. For more information, refer to the AT24C512 datasheet.
The QuickStart includes a 5 MHz crystal, for use when running at either 5 MHz without the use of a PLL, or 5, 10, 20, 40, or 80 MHz when used with the internal PLL. The Propeller can also run at nominal 20 kHz or 12 MHz using internal RC time constants. The 5 MHz crystal is connected through a surface-mount shunt, R13, which can be removed to disconnect the crystal. For custom crystal frequencies, remove the shunt and add another crystal to the unpopulated crystal socket, X2. The Propeller can also be driven through the XI line on the accessory connections, with or without the shunt present.
The Propeller's built-in brownout voltage detector is enabled, by default, through a surface-mount shunt, R12. For operation at or lower than 3.0V DC Vdd, move R12 from the position marked “On” on the PCB to the position marked “Off”. To ensure stability, use an external brownout voltage detector rated for 2.7V DC or higher.
The reset button, when pressed, will force the Propeller to reset which will cause it to reload any code present in the EEPROM.
Delta Sigma (ΔΣ) Digital to Analog Conversion
The unpopulated R14, R15, C16, and C17 pads are available for experimenting with Delta-Sigma modulation. R15 is the input resistor, R14 is the feedback resistor, and C16 and C17, in parallel, act as the capacitor. The plated-through just below R15 is the input, and the plated-through just below R14 is ground.
The Accessory Header, J1, includes connections for power, USB signals, and all Propeller I/O pins, including those used in the I2C bus and those used for USB communications.
P8X32A QuickStart Board Resources
Optional Recommended Products for this Item