An external programmer is needed for this target. The SAM4L has an internal bootloader you can use via an external serial port, which is not yet supported directly by the ChipWhisperer-Capture software.
=== JTAG Programmer ===
The 20-pin JTAG port (J6 on CW308 Board) can be used with the [https://www.digikey.com/product-detail/en/microchip-technology/ATATMEL-ICE/ATATMEL-ICE-ND/4753379 ATATMEL-ICE] which is Atmel's JTAG programmer. You can use any other ARM programmer you might have as well (i.e., OpenOCD, Segger J-Link, etc).
[[File:sam_jtag_small.jpg|400px]]
=== Using Atmel SAM-BA ===
Atmel SAM4L has a built-in bootloader. Not this bootloader is NOT ROM-Resident - if you reprogram the device the bootloader is lost, since it is stored in flash memory. It is recommended to use an external JTAG programmer for this target, as since the bootloader is not ROM-resident it can easily be overwritten by accident (i.e., if connecting a JTAG programmer).
== SimpleSerial Program ==
The SimpleSerial-AES program can be built for this target. This can use either hardware crypto or a software AES. This project is currently built via the Atmel Studio IDE, and the project file is located at [https://github.com/newaetech/chipwhisperer/tree/develop/hardware/victims/firmware/simpleserial-aes/ide_projects/asf/sam4l-simpleserial-aes hardware/victims/firmware/simpleserial-aes/ide_projects/asf/sam4l-simpleserial-aes] with the ChipWhisperer release.
If an Atmel ICE is attached as above, you should be able to build and run the example in 'debug' mode:
[[File:sam4l_ide.png|400px]]
An automatically generated makefile can be modified to built in Linux, but currently has not been integrated into the rest of the system. This makefile is checked into the GIT repository.
=== Adjusting Hardware AES ===
Inside the file ''hwaes.c'' you will find the AES hardware initilization. This is given in the following code sample:
<syntaxhighlight lang=c>
void aes_init(void)
{
periclk_aesa_init();
SCIF->SCIF_GCCTRL[AESA_GCLK_NUM].SCIF_GCCTRL = SCIF_GCCTRL_OSCSEL(GENCLK_SRC_CLK_CPU) | SCIF_GCCTRL_CEN;
/* AES Enable */
AESA->AESA_CTRL = AESA_CTRL_ENABLE | AESA_CTRL_NEWMSG; /* Enable, auto-accept new messages */
//Use with debugger to check PARAMETER register value
//volatile uint32_t param = AESA->AESA_PARAMETER;
/* AES Mode */
AESA->AESA_MODE = AESA_MODE_ENCRYPT | (AESA_MODE_CTYPE(0x0F)); /* Encrypt Mode, with all countermeasures */
//AESA->AESA_MODE = AESA_MODE_ENCRYPT; /* Encrypt Mode, without countermeasures */
/* Setup random seed for countermeasures to work */
AESA->AESA_DRNGSEED = 0xDEADBEEF; //A very random number
}
</syntaxhighlight>
Note there are two options shown, where countermeasures can be enabled or disabled. You can see the SAM4L datasheet for a description of the countermeasures. The following compares the power traces with and without countermeasures:
The following shows countermeasures enabled, you can see various execution paths taken during the encryption:
[[File:sam4l_wcountermeasures.png|600px]]
Compare this to the countermeasures disabled:
[[File:sam4l_nocountermeasures.png|600px]]
== Schematic ==
See GIT Repo for PDF of schematic.
[[File:CW308T-SAM4L-02_schematic_Page_1.png|1000px]]
[[File:CW308T-SAM4L-02_schematic_Page_2.png|1000px]]
== Board Layout ==
