CW308T-CEC1702

Multi-purpose AES Cryptographic Engine

- Hardware support for ECB, CTR, CBC, and OFB AES modes

- Support for 128-bit, 192-bit and 256-bit key length

- DMA interface to SRAM, shared with Hash engine

Cryptographic Hash Engine

- Support for SHA-1, SHA-256, SHA-512

- DMA interface to SRAM, shared with AES engine

Public Key Cryptographic Engine

- Hardware support for RSA and Elliptic Curve public key algorithms

- RSA keys length from 1024 to 4096 bits

- ECC Prime Field and Binary Field keys up to 640 bits

- Microcoded support for standard public key algorithms

Other Cryptographic Features

- True Random Number Generator  

- 1 Kbit FIFO  

- Monotonic Counter  

Creating and Modifying Examples

The following notes may prove useful when using mikroC PRO examples or creating your own:

• Any example which uses UART1 needs to be changed to use UART0 by changing the UART1_* functions to UART0_*.
• The plain text and encrypted text buffers need to be 16 byte aligned for the CEC1702's DMA to function properly. If the aes_crypt() call fails or the encryption never completes, this may be the cause. See simpleserial_base.c or mikroC PRO's AES examples for examples of this.
• All variable declarations need to be done at the beginning of functions, before any variables are modified or functions are called.
• The mikroC PRO compiler may have strange sizes for integer constants, meaning changing 4 8 bit numbers into a 32 bit number via bitshifts may not work as intended. Instead, using memcpy() may prove easier and more reliable.
• When using mikroC PRO's "Clean Project Folder", ensure that .mcpar, .c, .h, and .xml files are not selected, as this will cause the source/project/Flash Center
• The port base for use with the GPIO library is actually GPIO_PORT_xxx_xxx, not _GPIO_PORT_xxx_xxx. Additionally, this is not a pointer, meaning the address of this variable needs to be passed to the gpio functions
• There are no GPIO library functions to write or read from pins. Instead, use GPIO_OUTPUT_xxx_xxx.Bn/GPIO_INPUT_xxx_xxx.Bn for bit n of pin range xxx-xxx.

Compilation Settings

Project > Edit Project

Select CEC1702 in the MCU Name dropbox, change the MCU Clock Frequency to 48MHz.

If you want to program and run off of the SPI flash, additional configuration is needed:

> General Output Settings ...

Make sure Generate BIN image file is checked. Press OK on the window and the previous edit project window.

Build > Build

The messages dialog should indicate a successful build, and the image binary (PROJECTNAME_img.bin) and hex (PROJECTNAME.hex) can now be found in the project output folder. To confirm correct build settings, check the image binary using your SPI flash software or a HEX editor. The image binary should begin with the 8 bytes 01 00 00 3E 01 00 00 3E at offset 000000, and the rest of the program should begin at offset 000100.

Programming the SPI Flash

The SST26VF016B flash chip on the target board can be programmed by an SPI programmer attached to the SPI pins of the CW308. To program the chip, the nRST chip must be pulled to ground by holding the nRST button down or by connecting a jumper to J8 on the CW308. Additionally, the SDIC pin must be driven high during the programming process the enable communication through a buffer chip.

The SST26VF016B flash chip uses global block protection that must be disabled before every write operation. This is done by sending the command code 98 to the chip before erasing or writing to the device. This can be done by configuring a custom transaction in your flash programming software. Below is a table of useful information for configuring your programming software. The Parameters listed here have been tested with the Total Phase Flash Center software and the Aardvark I²C/SPI Host adapter. Additionally, a Total Phase Flash Center script is provided with the firmware for additional reference. See the SST26VF016B data sheet and the manual for your SPI flash program for more details.

Programming over JTAG/SWD

In addition to the SPI flash method, the CEC1702 can be temporarily (until power off) programmed using a JTAG debugger. This has been tested using Ozone V2.56d with a j-Trace Pro from Segger. The mikroC PRO IDE also supports programming and debugging using the Segger.

Note that the CEC1702 only supports JTAG when the Debug Select bit (Byte 482 Bit[6]) of EFUSE is 0 and SWD when the Debug Select bit is 1. If one does not work, try the other.

Load the image binary on to the flash chip and verify that the write was performed. If verification fails, ensure the nRST pin was held low for the entirety of the erase/write/verify cycle. If verification still fails, refer to the data sheet and your programming software manual to make sure the necessary command codes were sent in the appropriate order.

Running the Program

If you programmed the device via SPI flash, remove the nRST jumper/release the nRST button and disconnect the 3.3V source from PDIC. If you loaded your code from JTAG, hit go on your debugging software.