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Shield pin configuration
3.2
Intel® Edison kit for Arduino* PWM swizzler
There are four available GPIO that can be configured as PWM outputs. The PWM features are:
•
The PWM Output Frequency and Duty Cycle can be estimated by the equations:
•
Target frequency ~= 19.2 MHz * Base_unit value / 256
•
Target PWM Duty Cycle ~= PWM_on_time_divisor / 256
The four PWM sources are wired to a PWM “swizzler”. This pin header arrangement allows the four PWM sources to
be routed to any four of the six Arduino header pins. Figure 3 shows the PWM swizzler.
Figure 3
Intel® Edison kit for Arduino* PWM swizzler
The four PWM sources from the Intel® Edison compute module (GP12_PWM0, GP13_PWM1, GP182_PWM2, and
GP183_PWM3) can be configured to drive four of the six Arduino* header PWMs. Each Intel® Edison kit for Arduino
PWM can be jumpered to one of three Arduino PWMs. For example, GP12_PWM0 can be jumpered to PWM0_OUT,
PWM2_OUT, or PWM1_OUT.
Arduino* multiplexing has secondary multiplexing options of SPI (or GPIO). No other PWM has these secondary
multiplexing options. Therefore, if the four Intel® Edison compute module PWMs are used and are not connected to
the first four Arduino* PWM pins, then those unused pins of the first four pins cannot be used as a GPIO. They will
have any function; they cannot be inputs or outputs (Table 9).
Table 9
Intel® Edison kit for Arduino* PWM swizzler signal assignments
Digital pin
Uno
Uno
Edison I/O
Edison PWM
11
IO
PWM(5)
GP43 (SSP2_TXD)
PWM3
10
IO
PWM(4)
GP41 (SSP2_FS0)
PWM3, PWM2
9
IO
PWM(3)
GP183_PWM3
PWM3, PWM2, PWM1
6
IO
PWM(2)
GP182_PWM2
PWM2, PWM1, PWM0
5
IO
PWM(1)
GP13_PWM1
PWM1, PWM0
3
IO
PWM(0)
GP12_PWM0
PWM0
The factory default jumper configuration of Intel® Edison kit for Arduino* has digital pins 3, 5, 6, and 9 attached to
GPx_PWMx. These pins can be configured to be either a GPIO or a PWM output. The swizzler allows the four Intel®
Edison compute module PWMs to be mapped to the six Arduino* pins as shown in the last column of Table 9. For
example, if PWM0 is mapped to digital pin 5, then there is no Intel® Edison kit for Arduino* pin available to connect
to Digital pin 3. So this pin no longer has a function. If it is driven as an output, it will output high. If it is driven as an
input, the signal is lost in the swizzler.
The default configuration is DIG3 = GP12_PWM0, DIG5 = GP13_PWM1, DIG6 = GP182_PWM2, and DIG9 =
GP183_PWM3. This requires jumpers on J12 1-2, and J12 3-4, J11 1-2, and J11 3-4, as shown in Figure 4.
Intel® Edison Kit for Arduino*
December 2014
Hardware Guide
Document Number: 331191-004
15