SAM9X60-Curiosity – Configure and Build at91bootstrap to Load a MPLAB® Harmony v3 Application from NAND Flash Memory

Last modified by Microchip on 2024/05/13 13:37


This training describes how to download, configure, and build at91bootstrap to load an MPLAB® Harmony v3 Software Framework application binary image (harmony.bin) from NAND Flash Memory to DDR2 SDRAM on the SAM9X60-Curiosity Development Board using the MPLAB X Integrated Development Environment (IDE).  

Once at91bootstrap has been built, the resulting binary image (boot.bin) can be written to NAND Flash memory using the SAM-BA® In-System Programmer (ISP).  

at91bootstrap is a second-stage bootloader for Arm®-based Microchip Technology microprocessors (MPU). For more information see the "at91bootstrap: A Second Stage Bootloader for Microchip MPUspage.


  • MPLAB X IDE installed on the host computer 
  • MPLAB XC32 Compiler installed on the host computer 

This training was developed with MPLAB X IDE v6.20 and MPLAB XC32 Compiler v4.35.

Before You Begin

Before you begin configuring at91bootstrap, you will need some information from the production build of the MPLAB Harmony v3 Software Framework application. In this example, we use harmony.bin as our application image from the "SAM9X60-Curiosity – Getting Started with MPLAB Harmony 3 Development: CSP Application: rtt_periodic_timeout" training.

  1. NAND Flash Memory offset value to read harmony.bin
  2. The harmony.bin image size 
  3. The DDR2 SDRAM address to load harmony.bin

These values will be used to configure at91bootstrap in the steps below. 

4 Gb NAND Flash Memory

The SAM9X60-Curiosity has a 4 Gb (512M x 8) NAND Flash memory (U3) (Macronix MX30LF4G28AD-XKI). It is connected to the NAND Flash controller of the SAM9X60D1G. 

Download at91bootstrap

Create a Project Directory. 

For the purposes of this training, we’ll name our project directory at91bootstrap. 

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Download or clone at91bootstrap version 4.

Download or clone from the Linux4sam GitHub repository

This training was developed with at91bootstrap version 4.0.8.

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Open Project at91bootstrap

From MPLAB X IDE, select File > Open Project…

An Open Project dialog is displayed.  

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Find and select the at91bootstrap project directory.

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Click on the Open Project button.  

The at91bootstrap project will be displayed in the Projects pane (upper left) and in the at91bootstrap – Dashboard pane (bottom left). IDE Open Project

You may receive a Configuration Loading Error. This is due to an older version of the Device Family Pack (DFP) at the time of creating the at91bootstrap project. You will update the DFP to the latest version in the next steps. 

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Configure at91bootstrap Project Properties

Open at91bootstrap Project Properties. 

Open the at91bootstrap Project Properties using one of the following methods: 

  1. In the Projects pane, highlight at91bootstrap and click on the wrench icon in the at91bootstrap - Dashboard
  2. In the Projects pane, right-click on at91bootstrap and select Properties from the menu. 

The Projects Properties – at91bootstrap dialog box opens. 

If you received a Configuration Loading Error in the previous step, you may see a [Resolve] link next to a version of the DFP. Highlight the latest DFP and click on the Apply button. This will update the configuration to the latest DFP.  

Project Properties: Device

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In the Device drop down box, select SAM9X60D1G and click on the Apply button.

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Configure the MPLAB XC32 Compiler.

In the Categories pane, select Makefile

Enter the following text in the Build command and Debug build command boxes: 

make CROSS_COMPILE="C:/Program Files/Microchip/xc32/v4.35/bin/bin/pic32c-"

Enter the following text in the Clean command box: 

make mplabclean CROSS_COMPILE="C:/Program Files/Microchip/xc32/v4.35/bin/bin/pic32c-" 

Type the version number of the MPLAB XC32 Compiler on your host computer. In this step, we are using version 4.35. 

The installation location of the MPLAB XC Compiler versions can be found by selecting Tools > Options from the MPLAB X IDE toolbar. An Options dialog box will open. Select Embedded from the toolbar and select the Build Tools tab. 

When cutting and pasting, beware of hidden formatting characters. 

Project Properties: makefile

Click on the Apply button.

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Configure at91bootstrap to load harmony.bin from NAND Flash Memory.
In the Categories pane, select Kconfig and click on the Load button. 
Find the at91bootstrap project directory and select configs directory and then select sam9x60_curiositynf_uboot_defconfig and click on the Open button. Project Properties: Kconfig load default configuration

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Make the following changes: 

In this step, you are taking an existing default configuration and altering it to load the MPLAB Harmony v3 Software Framework application (harmony.bin) from NAND Flash memory. This makes configuration a little bit easier than starting from scratch. 

Expand Next Software Type and select the Load 4 MB into start of SDRAM radio button. 

Project Properties: kconfig: Next Software Type

Expand Demo Application Image Storage Setup.

Observe Flash Offset for Demo-App.  

This is the NAND Flash memory offset value to the application binary (here called Demo-App). This value is planned by the developer as part of the memory map of the NAND Flash memory.  

Observe the value 0x00040000, which is the value set in the default configuration.  

Take note of this value as you will use it when writing the application binary (harmony.bin) to NAND Flash memory using the SAM-BA Host Applet nandflash (see the "Learn More" section). 

Observe Demo-App Image Size.  

This is the image size of the application binary image (here called Demo-App) to be copied from NAND Flash to SDRAM memory by at91bootstrap.  

Observe the value 0x000c0000, which is the value set in the default configuration.  

It is important that the Demo-App Image Size is greater than the application binary size. In this example, harmony.bin is approximately 3 KB. Much smaller than the value set in the default configuration. 

Enter the address to load the application 0x23f00000 to The External Ram Address to Load Demo-App Image.  

This value should match the .text load address in the applications linker script (ddram.ld). This value is shown below for the rtt_periodic_timeout application. 

IDE Linker File

Click on the Apply and OK buttons.

This completes the configuration of the at91bootstrap project properties. 

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Build at91bootstrap

Build at91bootstrap. 

Build the at91bootstrap project using one of the following methods: 

  1. In the Projects pane, right-click on at91bootstrap and select Build from the menu. 
  2. Click on the Build icon (hammer) in the tool ribbon. 

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Observe the build is successful. 

Output pane Build Successful for a Project

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Note the location of boot.bin: 


The boot.bin file is the binary image of at91bootstrap. The boot.bin image can now be written to NAND Flash memory using the SAM-BA Host Applet nandflash. Instructions on how to do this is listed in the "Learn More" section below. 

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The at91bootstrap has been configured and built to load an MPLAB Harmony v3 Software Framework application from NAND Flash memory on the SAM9X60-Curiosity. 

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Learn More

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