Piccolo Boot ROM

This is what I need to work with the boot ROM in the TI Piccolo C2000 devices.

The Boot ROM is factory-programmed with boot-loading software. Boot-mode signals are provided to tell the bootloader software what boot mode to use on power up. The user can select to boot normally or to download new software from an external connection or to select boot software that is programmed in the
internal Flash/ROM. The Boot ROM also contains standard tables, such as SIN/COS waveforms, for use in math-related algorithms.

Section 3.5.11 is a security section.

When the emulator is connected, the GPIO37/TDO pin cannot be used for boot mode selection. In this case, the boot ROM detects that an emulator is connected and uses the contents of two reserved SARAM locations in the PIE vector table to determine the boot mode. If the content of either location is invalid, then the Wait boot option is used. All boot mode options can be accessed in emulation boot.

The default behavior of the GetMode option is to boot to flash. This behavior can be changed to another boot option by programming two locations in the OTP. If the content of either OTP location is invalid, then boot to flash is used. One of the following loaders can be specified: SCI, SPI, I2C, CAN, or OTP.

Page 34, 35 tms320f28068.pdf

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tms320f28068 JTAG

One thing I find missing from embedded digital design is simplicity. One thing I would like to do is boil a complex design down to some key components. First up is JTAG. This is one way an engineer or technician can interface with a embedded microcontroller, that is already connected to a circuit.

I am focusing on Texas Instruments c28x Piccolo MCUs. All information is from the TI website and relevant datasheets.

Pull up resistor means there is a resistance connected between it and the supply voltage, and pull down resistor means it is connected to ground. They are internal when using JTAG.

/TRST has a 2.2 k Ohm pull down resistance.

On the 2806x device, the JTAG port is reduced to 5 pins (TRST, TCK, TDI, TMS, TDO). TCK, TDI, TMS and TDO pins are also GPIO pins. The TRST signal selects either JTAG or GPIO operating mode for the pins. During emulation/debug, the GPIO function of these pins are not available. If the GPIO38/TCK/XCLKIN pin is used to provide an external clock, an alternate clock source should be used to clock the device during emulation/debug since this pin will be needed for the TCK function.

The headers are JTAG-based emulators - XDS510™ class, XDS560™ emulator, XDS100.

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Electrical Design Engineer, Minneapolis, Minnesota

Page 22, 33, 54, 69, 136 on the tms320f28068 datasheet.