TMS320F2810, TMS320F2811, TMS320F2812
TMS320C2810, TMS320C2811, TMS320C2812
SPRS174T –APRIL 2001–REVISED MAY 2012
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3.2.8 M0, M1 SARAMs
All C28x devices contain these two blocks of single access memory, each 1K x 16 in size. The stack
pointer points to the beginning of block M1 on reset. The M0 block overlaps the 240x device B0, B1, B2
RAM blocks and hence the mapping of data variables on the 240x devices can remain at the same
physical address on C28x devices. The M0 and M1 blocks, like all other memory blocks on C28x devices,
are mapped to both program and data space. Hence, the user can use M0 and M1 to execute code or for
data variables. The partitioning is performed within the linker. The C28x device presents a unified memory
map to the programmer. This makes for easier programming in high-level languages.
3.2.9 L0, L1, H0 SARAMs
The F281x and C281x contain an additional 16K x 16 of single-access RAM, divided into three blocks
(4K + 4K + 8K). Each block can be independently accessed hence minimizing pipeline stalls. Each block
is mapped to both program and data space.
3.2.10 Boot ROM
The Boot ROM is factory-programmed with boot-loading software. The Boot ROM program executes after
device reset and checks several GPIO pins to determine which boot mode to enter. For example, the user
can select to execute code already present in the internal Flash or download new software to internal
RAM through one of several serial ports. Other boot modes exist as well. The Boot ROM also contains
standard tables, such as SIN/COS waveforms, for use in math-related algorithms. Table 3-4 shows the
details of how various boot modes may be invoked. See the TMS320x281x DSP Boot ROM Reference
Guide (literature number SPRU095), for more information.
Table 3-4. Boot Mode Selection
(1)(2)
GPIOF4 GPIOF12 GPIOF3 GPIOF2
BOOT MODE SELECTED
(SCITXDA) (MDXA) (SPISTEA) (SPICLK)
GPIO PU status
(3)
PU No PU No PU No PU
Jump to Flash/ROM address 0x3F 7FF6.
A branch instruction must have been programmed here prior to 1 x x x
reset to re-direct code execution as desired.
Call SPI_Boot to load from an external serial SPI EEPROM 0 1 x x
Call SCI_Boot to load from SCI-A 0 0 1 1
Jump to H0 SARAM address 0x3F 8000 0 0 1 0
Jump to OTP address 0x3D 7800 0 0 0 1
Call Parallel_Boot to load from GPIO Port B 0 0 0 0
(1) Extra care must be taken due to any effect toggling SPICLK to select a boot mode may have on external logic.
(2) If the boot mode selected is Flash, H0, or OTP, then no external code is loaded by the bootloader.
(3) PU = pin has an internal pullup. No PU = pin does not have an internal pullup.
3.2.11 Security
The F281x and C281x support high levels of security to protect the user firmware from being reverse-
engineered. The security features a 128-bit password (hardcoded for 16 wait states), which the user
programs into the flash. One code security module (CSM) is used to protect the flash/ROM/OTP and the
L0/L1 SARAM blocks. The security feature prevents unauthorized users from examining the memory
contents via the JTAG port, executing code from external memory or trying to boot-load some undesirable
software that would export the secure memory contents. To enable access to the secure blocks, the user
must write the correct 128-bit ”KEY” value, which matches the value stored in the password locations
within the Flash/ROM.
34 Functional Overview Copyright © 2001–2012, Texas Instruments Incorporated
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