homework 6 solution

homework 6 solution - Assigned: 4/26/05 Completed by:...

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Assigned: 4/26/05 Completed by: 4/29/05 1 CprE 211 – Spring 2005 Homework 6 Grading Procedure for Homework: This homework will not be collected and not be graded. The solution will be distributed on-line one week later. Remember, these homework exercises not only give you practice with course concepts, but also represent the types of questions you will be tested on in an exam. I. QADC Programming Answer the following questions about the use of the QADC in an audio input application, which is summarized below. The QADC is the same unit as on the MPC555, however, in this application, it is part of a different microcontroller. Audio Input Application using the QADC The audio input node consists of a stereo input jack for audio input, typically from a personal CD player which connects to two of the QADC analog input pins. The QADC samples at approximately 60kHz, i.e. 30kHz per channel, and the data is passed to the TouCAN (a special network bus).
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Assigned: 4/26/05 Completed by: 4/29/05 2 The main objective of the microcontroller on the audio input side of the CAN bus is to sample the analog input using a fixed sampling rate and then transfer the data onto the CAN bus. The QADC will be used in software triggered continuous-scan mode which allows the QADC itself to control the sampling rate to 29.2kHz per channel, i.e. 58,400 samples per second. A single queue, queue 2, with maximum length of 40 conversions will be used to reduce the CPU overhead to a minimum. This queue will be configured to sample left audio channel on PQA0 and then right audio channel on PQA1 alternatively. Once all 40 conversions are complete and the queue is full, the QADC will generate an interrupt to request the CPU to empty the conversion result queue and transfer the data to the TouCAN module. Port pin PQA0 corresponds to analog input channel AN52, i.e., channel number 0x34. Port pin PQA1 corresponds to analog input channel AN53, i.e., channel number 0x35. Table 13-20: Channel Assignment for Pins Refer as needed to audio application note and chapter 13 of the MPC555 manual: http://class.ee.iastate.edu/cpre211/homework/qadc_audio.pdf http://class.ee.iastate.edu/cpre211/labs/c13qadc.pdf
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Assigned: 4/26/05 Completed by: 4/29/05 3 Questions: 1. Referring to section 13.12 Programming Model, from the QADC chapter in the MPC555 Manual (c13qadc.pdf file), which register is used to set up the QCLK period that determines the audio sampling frequency (this is different than the Input Sample Time in a CCW; it is the base QCLK for sampling the analog input channels). QADC64 Control Register 0 (QACR0)
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homework 6 solution - Assigned: 4/26/05 Completed by:...

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