Infineon AURIX User Manual

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AURIX™ TC3xx Microcontroller Training

V1.0.0

DMA_ADC_Transfer_1 for KIT_AURIX_TC375_LK

DMA transfer of ADC conversion results

Please read the Important Notice and Warnings at the end of this document

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Scope of work

The DMA is used to transfer ADC measurements results to CPU0 DSPR.

At the end of an analog-to-digital conversion of the Enhanced Versatile

Analog-to-Digital Converter (EVADC) module, an interrupt is triggered, which starts the data transfer of the converted ADC results via DMA to the CPU0 Data Scratch-Pad SRAM (DSPR0). The ADC conversion is started manually

via a command of a serial monitor.

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Introduction

› The Direct Memory Access (DMA) transfers data from data source locations to data

destination locations without intervention of the CPU or other on-chip devices

› A DMA channel performs transactions. One transaction is made of transfers. One transfer

is made of up to 16 moves. This structure divides the data into several parts and increases

the application’s efficiency

› A DMA move is an operation that always consists of two parts:

– A DMA read move that loads DMA read move data from a source module to the DMA – A DMA write move that stores DMA write move data from the DMA to a destination

module

› A transaction can be interrupted, however once a transfer is started, it cannot be interrupted › A move operation (8-bit,16-bit, 32-bit, 64-bit, 128-bit or 256-bit):

1. Loads data from the data source into the DMA controller

2. Puts data from the DMA controller to a data destination

› Any DMA move engine can service a DMA request from any of the 128 DMA channels.

Channel 127 has the highest priority

› Example:

– 1024 words (32-bit per word) transaction can be composed of 256 transfers of 4 DMA

word moves, or 128 transfers of 8 DMA word moves

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Introduction

› The Enhanced Versatile Analog-to-Digital Converter module (EVADC) of

the AURIX™ TC37x comprises 8 independent analog to digital converters

(EVADC groups) with up to 16 analog input channels each. Each,

converting with a resolution up to 12-bit

› Several request sources can request an Analog/Digital conversion

following different configurations. A conversion can be requested to be

done once or repeatedly

› Interrupts can be generated once conversions are finished

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This code example has been developed for the board KIT_A2G_TC375_LITE.

In this example, the pin AN0, connected

to the board’s potentiometer, is used.

Note: The channels can be HW filtered by the

board, depending on which capacitor/resistors

couples are soldered. Consult the AURIX™

TC375 lite Kit’s User Manual to check which channels are filtered by HW.

Note: The reference voltage (VAREF) of the

EVADC on the board KIT_A2G_TC375_LITE is 3.3 V.

Hardware setup

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Implementation

Application use case

The DMA_ADC_Transfer_1 example works as follows:

1. The user sends a ‘1’ character via a serial monitor

2. This triggers an Analog/Digital conversion

3. Once the conversion is done and the result written in the EVADC result register, an interrupt is

triggered

4. This interrupt calls a DMA transaction, since the DMA is configured as the Interrupt Service

Provider for this ADC interrupt

5. Once the transaction is finished, an interrupt is triggered by the DMA and handled by the CPU, to

send a feedback message to the user on the serial monitor

This sequence can be repeated at any time.

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Implementation

Configuration of the ADC

For this example, the configuration of one group using one single channel is sufficient. In init_EVADC(), the Analog-to-Digital converter is initialized and configured with the following steps:

› An EVADC module configuration structure is filled with default values using the function

IfxEvadc_Adc_initModuleConfig()

› The EVADC module is initialized using the function IfxEvadc_Adc_initModule() › An EVADC group configuration structure is filled with default values using the function

IfxEvadc_Adc_initGroupConfig()

› The group configuration is changed specifying several parameters, such as group ID, master, calibration

startup etc.

› The EVADC group is initialized using the function IfxEvadc_Adc_initGroup()

› An EVADC channel configuration structure is filled with default values through the function

IfxEvadc_Adc_initChannelConfig()

› The channel configuration is changed by specifying

– channelId the channel ID – resultRegister the result register where to store the result – resultPriority to trigger an interrupt every time a result is generated after a conversion; this is set

equal to the DMA channel to be triggered

– resultServProvider the Interrupt service provider: in this case, the DMA

› The EVADC channel is initialized using the function IfxEvadc_Adc_initChannel() › The configured queue is started (empty) with the function IfxEvadc_Adc_startQueue()

To do the conversion only once after being triggered, the channel is added to the queue when requested by

the user, through the IfxEvadc_Adc_addToQueue() function inside read_EVADC().

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Implementation

Configuration of the ADC (cont.)

The read_EVADC() function is starting the measurement and conversion of the analog values by adding the configured channel (with no refill option specified) to the queue with the function

IfxEvadc_Adc_addToQueue().

The read_EVADC() function is called from the while loop inside the Cpu0_Main.c file only if the

correct character (‘1’) is read by UART.

EVADC_G0RES0 @0xF0020700

Valid Flag set to 1

when a new result is

written. Reset to 0

once the result has

been read

12-bit result

after the

conversion

32-bit result register of Group 0 - Channel 0

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0x70000000 0x70000004 0x70000008 0x7000000C

Implementation

Configuration of the DMA

The needed transaction is configured in the init_DMA() function. Here, the number of transfers per transaction and the size of the word moves are defined.

In this example, we want to transfer a 32-bit result register from the EVADC. A single transaction

with one transfer made of one 32-bit word move is fitting. All of the above can be achieved with a single DMA channel (in this case: channel 1). The data source and destination locations are also set in the same function.

Additionally, the DMA channel is configured in such a way, that the source and destination addresses are not incremented after the transaction, since we always want to transfer from the same result register to the same location in the DSPR0. This is configured via the destinationAddressCircularRange and sourceAddressCircularRange parameters.

An interrupt on the DMA channel is configured in order to send a feedback to the user via UART when a transaction is completed. This service is provided by the CPU0.

DMA Controller

DMA

Channel

source

EVADC_G0RES0

0xF0020700 0xF0020704 0xF0020708 0xF002070C

destination

DSPR0

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Implementation

Configuration of the UART

In this tutorial, the UART connection is used to make the debugging more convenient and easier to understand.

The function init_UART() is initializing the UART communication. The iLLD function IfxAsclin_Asc_initModuleConfig() fills the configuration structure ascConf with

the default values. Then, the parameters are set to their correct value, depending on the needed connection: baudrate, Tx and Rx buffer size, Tx and Rx pin configuration etc.

Finally, IfxAsclin_Asc_initModule() initializes the module with the user configuration.

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Run and Test

› For this training, a serial monitor is required for sending inputs. The monitor can be opened

inside the AURIX™ Development Studio using the following icon:

› The serial monitor must be configured with

the following parameters to enable the

communication between the board and the PC:

– Speed (baud): 115200 – Data bits: 8 – Stop bit: 1

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After code compilation and flashing the device, perform the following steps:

› Connect the board to the PC › Open the serial monitor with the appropriate COM port and settings

› Send ‘1’ and pause the debugger

› The successful DMA transfer can be observed with the debugger by adding the below

address in the memory view at the same time (the byte values are shown in Little-Endian order):

– Check the memory at the DSPR0 address 0x70000000

– It matches the result of the EVADC peripheral result register *

› Send ‘1’ again to start another conversion

Run and Test

*80000FFFh to 00000FFFh because Valid Flag (VF, bit 31) is reset to 0 after reading the EVADC result

Conversion results

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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

characteristics (“Beschaffenheitsgarantie”).

With respect to any examples, hints or any typical values stated herein and/or any information regarding the application of the product, Infineon Technologies hereby disclaims any and all warranties and liabilities of any kind, including

without limitation warranties of non-infringement

of intellectual property rightsof any third party.

In addition, any information given in this document is subject to customer’s compliance with its obligations stated in this document and any applicable legal requirements, norms and standards concerning customer’s products and

any use of the product of Infineon Technologies in

customer’s applications.

The data contained in this document is exclusively intended for technically trained staff. It is the responsibility of customer’s technical departments to evaluate the suitability of the product for the intended application and the completeness of the product information given in

this document with respectto suchapplication.

For further information on the product, technology, delivery terms and conditions and prices please contact your nearest Infineon Technologies office (www.infineon.com).

WARNINGS

Due to technical requirements products may

contain dangerous substances. For information

on the types in question please contact your nearest Infineon Technologies office.

Except as otherwise explicitly approved by Infineon Technologies in a written document signed by authorized representatives of Infineon Technologies, Infineon Technologies’ products

may not be used in any applications where a

failure of the product or any consequences of the use thereof can reasonably be expected to result in personal injury.

Edition 2021-03

Published by

Infineon Technologies AG 81726 Munich, Germany

Do you have a question about this

document?

Email: erratum@infineon.com

Document reference DMA_ADC_Transfer_1_KIT_TC375_LK

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