263
Display Dimming Application Routine
Output a PWM signal with a varying duty cycle to control the brightness of a display. (VF, LED, etc.)
The schematic for this application is as follows:
Figure 17. Display Dimming Application
T1
SPI
TMS370
Microcontroller
T1PWM
I/O Pin
SPICLK
SIMO
ENABLE
CLKIN
DATA
Shift Register
Display
This application requires a PWM signal with a duty cycle which can vary from 0% to 100%. The resolution
of the signal is 0.5% (200 steps from 0% to 100%). The T1 module is used in this example, but T2n may be
used in a similar manner for those devices which contain T2n. Only the dimming function is covered in this
application. The SPI interface is illustrated in Using the TMS370 SPI and SCI Modules Application Report
(SPNA006).
Figure 18. Display Dimming PWM Signal
t1
t2
In this PWM application, the pulse width duty cycle (t
2
) may be changed under program control by altering
the value in the capture / compare register. The compare register controls the period of the signal (t
1
) and
is not changed in this routine.
*
Summary of Contents for TMS370 Series
Page 1: ...TMS370 Microcontroller Family Application Book 1996 8 Bit Microcontroller Family ...
Page 2: ...Printed in U S A February 1996 SPNA017 ...
Page 3: ...1996 Application TMS370 Microcontroller Family Book ...
Page 20: ...1 Part I Introduction ...
Page 21: ...2 ...
Page 22: ...3 Introduction Microcontroller Products Semiconductor Group Texas Instruments ...
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Page 86: ...67 RAM Self Test on the TMS370 Microcontroller Products Semiconductor Group Texas Instruments ...
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Page 90: ...71 ROM Checksum on the TMS370 Microcontroller Products Semiconductor Group Texas Instruments ...
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