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# 1.1.32 SAM RH71 Evaluation Kit: Building and Running the UART Bootloader applications

Downloading and building the application

To clone or download this application from Github, go to the main page of this repository and then click Clone button to clone this repo or download as zip file. This content can also be download using content manager by following these instructions

Path of the application within the repository is apps/uart_bootloader/

To build the application, refer to the following table and open the project using its IDE.

Bootloader application specifics for SAM RH71 Evaluation kit

The SAMRH71 Evaluation kits embed an external SST39VF040 memory on the board. This UART bootloader application for SAMRH71 Evaluation kit show how to configure the MH3 bootloader module and how to load a test application in this memory.

Test application specifics for SAM RH71 Evaluation kit

The test application is made to run at the base address of the external SST39VF040 memory that is mapped at address 0x60000000 by default.

After writing the test application inside the external SST39VF040 memory using the bootloader application in internal Flash, it is possible to modify the boot memory selection using the SW5 switch. In this case, the SAMRH71 device will boot directly from the external SST39VF040 memory. In that case, the application will take more time to start because the clock and HSMC access timings are reconfigured after the execution of the startup sequence. The first initialization will be executed at default reset clock configuration and with the worst case timing on the HSMC peripheral.

The default generated code has been modified in the test application example to workaround this constraint when the SAMRH71 boot directly on the test application:

- The watchdog is disabled directly in the Reset_Handler function: As is takes more time, the default watchdog time can expire before it is disabled in the application system initialization.

- The "ramfunc" attribute is added to the HSMC initialization function that modifies the read and write timing for the memory. When the application is already executing and fetching instructions from the external memory, we recommend executing the function that modifies the external memory configuration from a different memory. The "ramfunc" attribute will place and execute the HSMC initialization function in internal RAM.

Bootloader Application

Project Name | Description
--- | ---
bootloader/firmware/sam_rh71_ek_sst39.X | MPLABX Project for SAM RH71 Evaluation Kit

Test Application

Project Name | Description
--- | ---
test_app/firmware/sam_rh71_ek_sst39.X | MPLABX Project for SAM RH71 Evaluation Kit

Setting up SAM RH71 Evaluation Kit

- Power the board using J1 connector

- Connect the debugger probe to J33 on the SAMRH71-EK board

- Connect the J15 USB port of the board to a computer using a mini USB cable.

- Set the boot mode bootstraps pins to internal Flash, 8-bit prom width and disable ECC using dip switch SW5: (SW5.1 = 0, SW5.2 = 0, SW5.3 = 0, SW5.4 = 0, SW5.5 = 0)

Setting up the host script

- Refer to Bootloader Host Script Help for setting up the btl_host.py utility used to send the application binary from host PC

Running the Application

1. Open the test application project test_app/firmware/sam_rh71_ek_sst39.X in the IDE

2. Build the project to generate the binary (Do not program the binary)

3. Open the bootloader project bootloader/firmware/sam_rh71_ek_sst39.X in the IDE

4. Build and program the application on the SAMRH71 device using the IDE

5. Run the btl_host.py from command prompt to program the application binary

        python <harmony3_path>/bootloader/tools/btl_host.py -v -i <COM PORT> -d samrh71ek_prom -a 0x60000000 -f <harmony3_path>/bootloader_apps_uart/apps/uart_bootloader/test_app/firmware/sam_rh71_ek_sst39.X/dist/sam_rh71_ek/production/sam_rh71_ek_sst39.X.production.bin

6. Following snapshot shows output of successfully programming the test application

   - Rebooting and Reboot Done messages in below output signifies that bootloading is successful

7. If above step is successful then the LED1 should start blinking

8. Open the Terminal application (Ex.:Tera Term) on the computer

9. Configure the serial port settings as follows:

   - Baud : 115200
   - Data : 8 Bits
   - Parity : None
   - Stop : 1 Bit
   - Flow Control : None

10. Reset or Power cycle the device

11. LED1 should start blinking and you should see below output on the console

12. Press and hold the Switch SW0 to trigger Bootloader from test application and you should see below output

13. Repeat Steps 5-11 once and jump to Step-14.

    - This step is to verify that bootloader is running after triggering bootloader from test application in Step 12

14. Press and hold the Switch SW0 and then press Reset button or Power cycle the device to force trigger bootloader at startup

15. Repeat Steps 5-11 once

    - This step is to verify whether bootloader is triggered by switch press at reset

Additional Steps (Optional)

- To bootload any other application refer to Configuring an application to be bootloaded for CORTEX-M based MCUs