platform_ldma_trigger_with_timer

Platform - LDMA trigger with TIMER

Overview

This project demonstrates the usage of both the LDMA and VDAC peripherals to generate a fixed frequency sine wave using TIMER0 as a trigger source. For storing the values of the sine wave, the LDMA peripheral is used, which can either be triggered via PRS or directly by the TIMER0_CC0.

Gecko SDK version

• GSDK v4.4.4

Hardware Required

• EFR32xG24 Wireless 2.4 GHz +10 dBm Radio Board

• Wireless Starter Kit (WSTK) Mainboard (SLWMB4002A, formerly BRD4002A)

Note:

• Tested boards for working with this example:

  Board ID	Description
  BRD4210a	EFR32XG23 868-915 MHz +20 dBm Radio Board
  BRD4186c	EFR32xG24 Wireless 2.4 GHz +10 dBm Radio Board
  BRD4270b	EFR32FG25 902-928 MHz +16 dBm Radio Board
  BRD4400c	EFR32xG28 2.4 GHz BLE and +14 dBm Radio Board

Connections Required

Connect the board via the connector cable to your PC to flash the example.

Setup

To test this application, you can either create a project based on an example project or start with an "Empty C Project" project based on your hardware.

Create a project based on an example project

1. Make sure that this repository is added to Preferences > Simplicity Studio > External Repos.

2. From the Launcher Home, add your product name to My Products, click on it, and click on the EXAMPLE PROJECTS & DEMOS tab. Find the example project filtering by "ldma".

3. Click the Create button on Platform - LDMA trigger with TIMER example. Example project creation dialog pops up -> click Create and Finish and the project should be generated.

4. Build and flash this example to the board.

Start with an "Empty C Project" project

1. Create an Empty C Project project for your hardware using Simplicity Studio 5.

2. Copy all files in the inc and src folders into the project root folder (overwriting the existing file).

3. Install the software components:

   3.1. Open the .slcp file in the project

   3.2. Select the SOFTWARE COMPONENTS tab

   3.3. Install the following components:

   • [Platform] → [Peripheral] → [VDAC]

   • [Platform] → [Peripheral] → [LDMA]

   • [Platform] → [Peripheral] → [PRS]

   • [Platform] → [Peripheral] → [TIMER]

   • [Platform] → [Peripheral] → [Init] → [GPIO Init] → instance name: timer

4. Build and flash the project to your board.

How It Works

The example uses the timer's (TIMER0) compare channel (CC0) to trigger the VDAC conversion via an LDMA memory to peripheral transfer. The number of samples of the generated sine wave is specified by the SINE_TABLE_SIZE macro and is used by the LDMA as a single descriptor looped transfer.

The application defines the PRS_MODE macro to switch between the default timer connection interface and the PRS peripheral to connect the timer and the LDMA request line together.

When the timer connection interface is used (PRS_MODE = 0), TIMER0 requests a transfer start via the CC0 directly routed to the LDMA peripheral.

When PRS is used (PRS_MODE = 1), the peripheral utilizes the prsConsumerLDMA_REQUEST0 consumer line for the transfer's initiation.

A specific output frequency of the sine wave can be configured via the TIMER0_FREQ macro, which also takes the number of sampling points into account.

For an aditional debug option, the application defines the TIMER_DEBUG macro, which outputs the TIMER0_CC0 signal to one of the GPIOs:

Pin Routing

Output pin	BRD4210a	BRD4186c	BRD4270b	BRD4400C
VDAC0_CH0_MAIN_OUT	PB0	PB0	PB0	PB0
SL_EMLIB_GPIO_INIT_TIMER_PIN	PA5	PA5	PA5	PA11