Infineon GPT12 Timer Concatenation 1 Installation guide

AURIX™ TC2xx Microcontroller Training
V1.0.0
GPT12_PWM_Generation_1
for KIT_AURIX_TC297_TFT
Generation of PWM via GPT12
Please read the Important Notice and Warnings at the end of this document

Scope of work
A pulse width modulated (PWM) signal with fixed frequency and a
defined duty cycle is generated using GPT12.
The timer T3 of GPT1 is used in timer mode with its count direction
configured to “down-counting”. On underflow of timer T3, the Output Toggle
Latch (T3OTL) is toggled and the value of timer T2 or T4 is transferred into
timer T3 depending on T3OTL value. The state of an LED is toggled in an
interrupt service routine which is triggered by the timer T3.
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Introduction
›The General Purpose Timer Unit (GPT12) is made of two GPT blocks
(GPT1 and GPT2).
›Each block has a multifunctional timer structure which incorporates
several 16-bit timers.
›Block GPT1 contains three timers: the core timer T3 and two auxiliary
timers T2 and T4.
›All three timers of block GPT1 can run in one of four modes: Timer Mode,
Gated Timer Mode, Counter Mode or Incremental Interface Mode.
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Hardware setup
This code example has been
developed for the board
KIT_AURIX_TC297_TFT_BC-Step.
LED D107 (1) is used for this
example.
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Implementation
Configure the GPT12 Module
To generate a PWM signal with the GPT1 block, it is needed to:
›Enable the GPT12 module
›Configure the frequency for the block GPT1 by setting the prescaler value (BPS1)
of the divider
›Configure the frequency for the timer T3 by setting the prescaler value (T3I) of the
divider
›Configure the timer T3 mode, direction and starting value
›Configure the two auxiliary timers (timer mode, reload input mode and reload
values) to reload the timer T3
The above steps are detailed in the following slides.
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Implementation
Configure the GPT12 Module
Configuration of the GPT12 is done once in the function initGpt12PWM() by the
following steps:
›Enable GPT12 module by calling the iLLD function IfxGpt12_enableModule()
›Set GPT1 prescaler with the iLLD function IfxGpt12_setGpt1BlockPrescaler()
›Configure the mode of timer T3 by using the iLLD function
IfxGpt12_T3_setMode()
›Set the counting direction of the timer T3 by calling the iLLD function
IfxGpt12_T3_setTimerDirection()
›Set the prescaler of timer T3 by calling the iLLD function
IfxGpt12_T3_setTimerPrescaler()
›Set the timer value with the iLLD function IfxGpt12_T3_setTimerValue() and use
an uint16 number as parameter
The configuration functions above are provided by the iLLD header IfxGpt12.h.
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Implementation
Reload Values calculation example
Calculating the correct reload value to generate a PWM signal, depending on the given
frequency f and duty cycle, is done in the initialization function initGpt12PWM():
›Get the GPT12 module base frequency 𝑓
𝐺𝑃𝑇 by calling the iLLD function
IfxGpt12_getModuleFrequency()
›Calculate the timer frequency with the following formula:
The GPT1 block prescaler is set to IfxGpt12_Gpt1BlockPrescaler_32, 𝑓
𝐺𝑃𝑇 is divided by 32
The timer prescaler is set to IfxGpt12_TimerInputPrescaler_32, 𝑓
𝐺𝑃𝑇 is divided by 32
›Calculate dutyUpTime and dutyDownTime with the following formulas:
𝑓𝑡𝑖𝑚𝑒𝑟 =𝑓
𝐺𝑃𝑇
GPT1_BLOCK_PRESCALER ×TimerInputPrescaler
𝒅𝒖𝒕𝒚𝑼𝒑𝑻𝒊𝒎𝒆 = 𝑓𝑡𝑖𝑚𝑒𝑟 ×𝑑𝑢𝑡𝑦𝐶𝑦𝑐𝑙𝑒
100
𝑓𝒅𝒖𝒕𝒚𝑫𝒐𝒘𝒏𝑻𝒊𝒎𝒆 =
𝑓𝑡𝑖𝑚𝑒𝑟 × 1 − 𝑑𝑢𝑡𝑦𝐶𝑦𝑐𝑙𝑒
100
𝑓
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Implementation
Configuring timers T2 and T4 to enable the reload of timer T3
Configurations of timers T2 and T4 are done once in the function initGpt12Timer() by the
following steps:
›Configure timers T2 and T4 in reload mode by using the iLLD function
IfxGpt12_T2_setMode() and IfxGpt12_T4_setMode()
›Set the trigger event for reload of timer T3 by using the iLLD functions
IfxGpt12_T2_setReloadInputMode() and IfxGpt12_T4_setReloadInputMode()
›Set timer T2 value with the iLLD function IfxGpt12_T2_setTimerValue() and
dutyDownTime as parameter
›Set timer T4 value with the iLLD function IfxGpt12_T4_setTimerValue() and
dutyUpTime as parameter
Starting timer T3
Finally, starting the timer T3 is done in the function runGpt12PWM() by calling the iLLD
function IfxGpt12_T3_run().
The above functions are provided by the iLLD header IfxGpt12.h.
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Implementation
Configuring the interrupt for GPT12
Configuration of the interrupt is done once in the function initGpt12Timer() by the
following steps:
›Get the address of timer T3 service request with the iLLD function
IfxGpt12_T3_getSrc()
›Initialize GPT12 interrupt by calling IfxSrc_init() with a pointer to the address of
the timer T3 service request, the interrupt provider and the interrupt priority
number as parameters
›Enable GPT12 interrupt with the iLLD function IfxSrc_enable() and the pointer to
the address of timer T3 service request as parameter
The function IfxGpt12_T3_getSrc() is provided by the header IfxGpt12.h and the
functions IfxSrc_init() and IfxSrc_enable() are provided by the header IfxSrc.h.
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Implementation
Configuring the LED
The LED is configured and toggled by controlling the port pin to which it is connected.
In the setup phase, the port pin is configured as output push-pull mode using the
function IfxPort_setPinMode().
The Interrupt Service Routine (ISR)
The ISR implemented in this example calls the iLLD function IfxPort_togglePin() to
toggle the LED‘s state.
The interrupt is triggered every time the timer T3 generates an underflow.
On underflow of timer T3, the Output Toggle Latch (T3OTL) is toggled and the value
of timer T2 or T4 is transferred into timer T3 depending on T3OTL value.
Both functions are provided by the iLLD header IfxPort.h.
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Run and Test
After code compilation and flashing the device, observe the LED D107 (1),
which should be blinking 2 times in
a second.
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References
›More code examples can be found on the GIT repository:
›https://github.com/Infineon/AURIX_code_examples
›For additional trainings, visit our webpage:
›https://www.infineon.com/aurix-expert-training
›AURIX™ Development Studio is available online:
›https://www.infineon.com/aurixdevelopmentstudio
›Use the „Import...“ function to get access to more code examples.
›For questions and support, use the AURIX™ Forum:
›https://www.infineonforums.com/forums/13-Aurix-Forum
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IMPORTANT NOTICE
The information given in this document shall in no
event be regarded as a guarantee of conditions or
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values stated herein and/or any information
regarding the application of the product, Infineon
Technologies hereby disclaims any and all
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without limitation warranties of non-infringement
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Technologies office (www.infineon.com).
WARNINGS
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contain dangerous substances. For information
on the types in question please contact your
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signed by authorized representatives of Infineon
Technologies, Infineon Technologies’ products
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Edition 2020-06
Published by
Infineon Technologies AG
81726 Munich, Germany
© 2020 Infineon Technologies AG.
All Rights Reserved.
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Document reference
GPT12_PWM_Generation_1
_KIT_TC297_TFT
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