AN1921 Motorola / Freescale Semiconductor, AN1921 Datasheet - Page 15

• Manufacturer Part Number: AN1921
• Description: AN1921 General DSP568xx Interface Examples using the Embedded SDK
• Manufacturer: Motorola / Freescale Semiconductor

4.
Code Example 3.
If the interface between the SPI0 and the TLC2543 is correct, the ADC output data should be
seen as shown in the upper signal in
obtained by applying the second oscilloscope probe to the SPI0’s MISO port. The exact
appearance of this signal is highly dependent on the nature of the data being digitized by the
ADC on the prototype board; in contrast, the signals’ appearances in Figure 10, Figure 11, and
Figure 12 are fairly static in appearance over the period of the run.
If output data does not appear as expected, check all connections. Make sure that the ground systems
are securely connected on all subsystems if noise occurs. This advice applies to all circuits discussed in
this paper.
Earlier sections of this note established the ease of interfacing to various devices, such as an
LCD/keypad display and an 11-channel, 12-bit analog-to-digital converter. Remember that in the
descriptions of interfacing the MPX4115A with the TLC2543 and the DSP, the barometric
measurements were collected, but the debugger was required to see the results. By combining the
LCD/keypad and the ADC located on the DSP’s SPI0 port, it is now possible to show, in nearly
real-time, the measurements collected and processed on the LCD display, using the code shown in
Code Example
interfaced to an atmospheric transducer.
Integrating Devices With the EVM Board
/* IntFaceBaro.c - Procedure used to interface to TLC2543 - 12-bit analog-
to-digital converter with serial control and 11 analog inputs. The
DSP56824 SPI0 port is employed. The software is developed for the
DSP56824 EVM environment. Jan 26, 2001 */
IntFaceBaro.c
3. This code, IntFaceBaro.c, shows use of both LCD/keypad and TLC2543 ADC chip,
Interface Examples Using the Embedded SDK
Figure 10. ADC Data
Figure 10
. This figure shows the ADC output data signal
Integrating Devices With the EVM Board
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