Motorola MCU 68HC912 Instrukcja Użytkownika Pobierz pdf (Strona 2)

SLAA108A

2 SPI-Based Data Acquisition/Monitor Using the TLC2551 Serial ADC

Microcontroller

ADC

DAC

MISO

MOSI

SCLK

SS/CS

Signal Input

Reconstructed

Output

I/O

Introduction

The TLC2551 ADC requires a falling clock edge while the chip select pin is in the high state in

order to release the output data. This requirement can be satisfied by writing to a second device

on the serial bus, while holding the ADC’s chip select pin high. This application report describes

how to use the TLC2551 ADC in conjunction with the TLV5616 DAC, creating a complete data

acquisition system.

In this application report, an I/O pin on the microprocessor is assigned to perform the duties of

frame sync for the digital to analog converter. The DAC’s chip select pin is permanently held

low. An alternative approach would be to use the inverted output of the SS/CS pin from the

microcontroller as the DAC chip select.

The output from the TLV5616 can be used as the feedback signal in a control loop or as a

system monitor.

Figure 1. System Block Diagram

1 2 3 4 5 6 7 ... 13 14

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Motorola MCU 68HC912 Instrukcja Użytkownika Strona 2