I2C Startup and Boot

Hi Arya,

Arya Stark said:

1. When the DSP wakes up, it starts reading from the Eeprom. If I understand correctly, the first thing it reads is the parameters table from addresses 0-128 of the Eeprom. I see this happens with a clock of around 4.63KHz. How is this the rate? From what is it derived?

The PLL and I2C clock speed is configured by the ROM boot loader. The PLL is configured by the ROM bootloader in either x9 or x19 mode. Please refer the Bootloader User Guide (spruec6d) Section4.2. CFG[4] decides either to use x9 or x19 mode.

This configuration is used to read only the boot parameter table from the I2C EEPROM. The I2C boot parameter table then defines the I2C clock speed and PLL multiplier. See the following boot parameter table for C6472 EVM:

0x00000001  /* Contains one table only */
0x00200000  /* Here begins Boot Parameter table: length, checksum */
0x01010000  /* boot mode = I2C, port # = 0*/
0x001C0001  /* swPll=28, boot option = 1 = boot table */
0x00800050  /* dev addr low = 0x0080, dev addr high = 0x50*/
0x00000001  /* broad cast addr, device id */
0x02BC0064  /* core freq=28*25MHz=700 MHz, I2C bus freq = 100 KHz*/
0x00000000  /* next addr low = 0x00, next addr high = 0x00 */
0x00000000  /* address delay=0, reserved = 0x0 */

Arya Stark said:

2. Is there any way for me to read the boot parameters table? I can change the boot application with the post example given with the EVboard, but I don't see how to change (or even read) the I2C parameters.

The boot parameter tabe for the I2C EEPROM image generated is located at <evmc6472\bootloader_package\EEPROM_flash_image_gen\I2Cboot\input\i2cconfig.txt>.

You can change the boot parameter table settings by modifying this i2cconfig.txt file. Details of all the fields of boot parameter table is provided in section 4.3.2.2-3 of the Bootloader User Guide.

Hope this answers you queries.

Thanks,

Amit