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EsduinoXtreme User Guide - Hardware Details

Article Index
EsduinoXtreme User Guide
Overview of Features
Setting Up the Hardware
Application Programming
Software Debugging
Software Considerations
Software Considerations - Interrupts
Software Considerations - S12 Clock
Hardware Details
All Pages

Hardware Details

Input/Output Connectors

The four main I/O connectors follow the Arduino Leonardo standard for pincount and location, and attempt to match up signals from the MCU to similar signal types used on Arduino Leonardo.  Additionally, a 6-pin header bringing out the SPI pins is implemented in the same physical location of the board, to provide compatibility with shields that depend on this feature (Note:  due to a circuit board layout error, the pinout of this connector on Rev. 1 EsduinoXtreme is incompatible with Arduino shields; this will be corrected on the Rev. 2 board).  Unused pins on this header have been assigned to VDD so as to make the header more versatile.

Since the S12GA240 MCU has a higher pincount than the Atmel MCU used on Arduino Leonardo, there are some extra choices that have been implemented with jumper blocks so that the user can decide assignments on an application-by-application basis.

I2C implementation:  since the S12GA240 does not have a dedicated I2C subsystem, I2C functions must be bit-banged in software via the assigned pins connected to J3 pins 9 and 10 (or via any other convenient pins).

The EsduinoXtreme feature sheet details the signals for each header pin, using the pin names shown in Freescale documentation. Note that several pins can have more than one function, depending on how the hardware registers are configured. Furthermore, some hardware subsystems can be re-mapped to different ports. Refer to the Freescale manual for the MC9S12G for details.

Voltage Regulator Configuration

EsduinoXtreme has two on-board regulators:  U2 supplies 5V and U3 supplies 3.3V.  U2 takes the filtered DC voltage (6-12 VDC) applied to one of the optional VIN connectors (J6 and J7) or applied to the VIN pin on header J4 and provides a smooth regulated 5 Volts DC to the components.  When jumper block JB1 is set to VIN, this 5V rail is active.  Otherwise, 5V comes from the USB connector, and U2 is not used.  In either case, the 5V rail is fed to 3-Volt regulator U3, which produces a 3.3V output for use when the MCU operating voltage is set via JB7 to 3V, and which also appears at the 3V3 pin on header J4, for use by application shields, if required.  The 3V supply is also used to power the optional XBee module if it is attached via user-installed header J10, since it is a 3V device.

If you plan to use the on board regulators to power your own circuits in addtion to the module, please be aware that the regulators are rated to supply a maximum of 700 mA total current each, but the total current draw will be limited if the system is powered via the USB port instead of an external power supply.  Another limiting factor is heat.  At room temperature, the regulator by itself will only be able to dissipate about two watts of heat.  The amount of dissipation needed will depend both on the input voltage applied, and the current drawn to feed the electronics.  So a power supply at 6 volts will not cause the regulator to heat up as much as a 12 volt supply will.  If you need to dissipate more heat than two watts though, you must add a heat sink to the regulator.


Last Updated ( Friday, 08 February 2019 18:14 )