Datasheet

I2C Bootloader
Document Number: 001-13258 Rev. *J Page 12 of 39
Specifies the range of CPU clock speeds under which a CY8C27xxx silicon revision A device oper-
ates. The CY8C27xA refers to the older CY27xxx devices that are no longer recommended for new
designs. In the PSoC Designer device catalog, the CY8C27x silicon revision A are at the bottom of
the catalog and are preceded with a “Not Recommended for New Designs" notice. They can be differ-
entiated from the new version in that the new versions of the parts have the letter ‘X’ in the part name.
The letter X is used to designate Pb-free parts. This parameter is needed to ensure that special code
handling is inserted at higher CPU clock speeds and eliminated to avoid unnecessary overhead at
lower CPU clock frequencies.
Parameters defined for the bootloader enable you to define where a major program block is located
when the program is compiled and linked. In some cases, a project may be developed on a 27xxx
POD that uses an older revision of silicon (and so requires these clock speed specific settings), while
the target part is a newer version of silicon. No significant project impact is experienced by including
the clock speed parameters appropriate for older silicon in newer devices.
ApplicationCode_Start_Block
This is the first block of code assigned to the User Application. This code must be bootloadable/write-
able. This parameter is also used by the Bootloader Tools to determine which blocks of code should
be processed for a .dld file and which blocks of code to calculate checksums on. This variable is prop-
agated into the checksum block for use when the bootloader utility automatically verifies the applica-
tion checksum.
The default address specified by the parameter block default may be calculated by multiplying the
device block size (0x40 or 0x80) times the block in the parameter.
Bootloader_Key
This is the key value prepended to the transactions sent to the bootloader application, representing
an extra verification step. This step ensures that the bootloader upgrade utility is not accidentally
invoked.
The default value "0001020304050607".
Flash_Program_Temperature_Deg_C
This is the typical programming temperature expected when the device is reprogrammed. Program-
ming the device at a different temperature than that specified in this parameter may adversely effect
program retention.
Matching the program temperature parameter to the actual temperature during bootload impacts
memory retention and the maximum number of write cycles. PSoC implements a stronger flash write
CPU_Clk_speed_(CY8C27xA) value Use
6 MHz or less Use this setting if the CPU clock speed is 6 MHz or less. This eliminates
any unnecessary code.
Above 6 MHz (CY8C27x A ONLY) Use this setting if the CPU clock speed is above 6 MHz and the chip used
is from the CY8C27xxx silicon revision A family. This ensures proper
functionality of the user module at the cost of some additional overhead.
Not CY8C27xA Use this setting for any chip outside the CY8C27xxx silicon revision A
device family. This applies to any CY8C29/24/22xxx part or the
CY8C27xxx parts that have the letter ‘X’ in their part number in the device
catalog. Choosing this value eliminates unnecessary code.