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Failure to Capture Input During Cascade Connections

Last Updated:06/08/2017

Question:

I tried to capture MTU1.TCNT and MTU2.TCNT simultaneously using a single input capture with cascade connection, but it does not work properly. What are the possible causes?

Answer:

Please check the following items:

(1) Input capture setting enabled both for MTU1 and MTU2

The input capture for MTU1 is taken as the input capture for MTU2 internally and vice versa. Therefore, MTU1 and MTU2 should be set at the same value in the timer I/O control register (TIOR) setting. 

(2) Terminals not used for input capture set high

When the I2AE bit of the input capture control register (TICCR) is set to "1", the input capture terminal of MTU1 becomes both MTIOC1A and MTIOC2A. At this time, edge detection for the input capture condition is performed at the signal from a logical OR of MTIOC1A and MTIOC2A terminal input levels, and if one of the inputs is high, no edge detection happens even if the other one changes. 
Change the terminal not used for input capture to low or specify its terminal function to something besides MTU (such as general I/O port).
When the terminal function is set to something besides MTU (such as general I/O port), it is internally tied low.

Suitable Products
RX110
RX111
RX113
RX210
RX21A
RX220
RX62N, RX621
RX62T
RX62G
RX630
RX63N, RX631
RX63T
RX64M
RX71M
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