User manual

In-circuit debugging UM0036
226/385 Doc ID 7705 Rev 11
STVD attempts to connect to the microcontroller on your application board. If the connection
fails, an error message is displayed, and you must change your MCU selection.
Caution: The MCU selection in the ICD MCU configuration window must match the MCU selected in
your project settings. If it doesn’t, you must open the Project Settings window, select the
appropriate MCU, and rebuild your application.
Note: When the dialog box opens for the first time, only the MCU selection tab is available.
Options tab
This interface lists the option bytes and their current values, and allows you to configure the
values from a list of available settings for your MCU (see Section 7.1.4: Configuring option
byte settings).
7.1.3 Ignoring option bytes (ICC only)
When establishing the initial connection with your microcontroller, option bytes may present
a problem if some settings are not consistent with your application. Inconsistent settings can
result in an MCU failure. For example, the clock source option byte must identify the correct
clock source. If the option byte is set to identify an external clock that is not in your
application, then your MCU won’t start for lack of a clock signal.
As a security, to avoid this kind of failure, STVD can start your microcontroller using the
external clock signal provided via the ICC add-on. This allows STVD to establish
communication with your microcontroller without taking into account the current values of
the MCU’s option bytes.
To do this, check the Start with external clock (ignore option bytes) checkbox in the ICD
MCU configuration dialog box (see Figure 162). Once STVD has established
communications with your MCU, you can confirm and reconfigure the option byte settings in
the Options tab of the ICD MCU Configuration dialog box, if necessary.
Note: 1 In order to provide an external clock signal to start your MCU, the MCU’s clock pin must be
relayed to the OSC_CLK pin of the HE10 connector on your application board. For
information about this connection, refer to your hardware user manual.
2 If this option is not supported by your microcontroller, it is grayed out as shown in
Figure 162, and you cannot check the check box.
7.1.4 Configuring option byte settings
Option bytes give you control of a range of ST microcontroller features such as low voltage
detection, oscillator source and range, watchdog behavior and memory read/write
protection. Option byte features vary from one microprocessor to another. For more
information about these features for your target MCU, refer to the corresponding datasheet.
Note: You can only configure option byte settings once STVD has established the connection to
your microcontroller.
Option bytes and ICD compatibility
Some option byte settings are not compatible with in-circuit debugging and, therefore, must
be configured to be consistent with ICD requirements. Option byte settings that are not
compatible with ICD are listed in Tabl e 71.