AN2366_NITC - Application Note AN2366/D Rev. 0, 10/2002...

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This TPU Programming Note is intended to provide simple C interface routines to the new input transition/input capture TPU function (NITC). 1 The routines are targeted for the MPC500 family of devices, but they should be easy to use with any device that has a TPU. 1 Functional Overview The NITC function can detect rising and/or falling input transitions. When a transition is detected, a value is captured. The value can be either a free-running incrementing counter value, known as the current Timer Count Register (TCR), or a parameter RAM value. The channel continues to detect and count input transitions until it has counted a programmable number of transitions. The NITC function can count the programmed maximum number of transitions once, ceasing channel activity until reinitialized, or the channel may perform this operation continuously. When the programmed number of transitions is counted, the function can send an interrupt request to the host CPU and/or generate a link request message to a sequential block of up to eight TPU channels. A link request is a message from one TPU channel to another TPU channel requesting service for the channel(s) receiving the link. The user specifies the starting channel of the sequential block and the number of channels to receive a link within the block. 2 Detailed Description Any channel of the TPU can perform an input capture by detecting either a rising edge, falling edge, or both edges of an input transition. Performing an input capture means to record the TCR value, or a parameter RAM value when an input transition occurs. The TPU is initialized differently depending on which value, a TCR value or a parameter RAM value is to be captured when a transition is detected. The function tpu_nitc_init_tcr_mode is used to initialize the TPU channel for TCR capture, and the function tpu_nitc_init_parameter_mode is used to initialize the TPU channel for parameter RAM capture. Any channel of the TPU can count several input transitions with the maximum number of transitions to be counted specified in the initialization routines or by the function tpu_nitc_write_max_count. An initial count of transitions detected can be set to some initial value by the function tpu_nitc_write_trans_count. The TPU services each input transition detected by saving a TCR value or a parameter RAM value. The function tpu_nitc_read_last_trans_time can be used to 1 The information in this Programming Note is based on TPUPN02 and TPUPN08. It is intended to compliment the information found in those Programming Notes. Application Note AN2366/D Rev. 0, 10/2002 Using the New Input Transition / Input Capture TPU Function (NITC) with the MPC500 Family
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2 Using the New Input Transition/Input Capture TPU Function MOTOROLA NITC Routines read the TCR value or parameter RAM value TPU_INTC_LAST_TRANS_TIME for each transition detected when the transition count is less than the parameter TPU_INTC_MAX_COUNT. The function tpu_nitc_read_final_trans_time
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AN2366_NITC - Application Note AN2366/D Rev. 0, 10/2002...

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