STMicroelectronics STM32 Series, Примечание к применению

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Troubleshooting AN4989
94/118 AN4989 Rev 3
11 Troubleshooting
Table 6 summarizes solutions to overcome some of the most frequent issues faced during
debug setting and operation.
Table 6. Troubleshooting
Problem Solution
Connection with target lost during debug of low-power
system
Ensure debug in low-power in DBGMCU register is
enabled.
Ensure SWD pin not set in analog state.
Refer to
Section 4.1: SWD/JTAG pinout and to
Section 4.3: Low-power case .
Fail to get printf via SWO Refer to Section 7.3: Printf via SWO/SWV .
An unexpected power consumption is measured for a
low-power application.
Check that low-power debug in DBGMCU register is
OFF. Beware that this register is reset only with a POR
(power-on reset).
Refer to
Section 4.3 .
Fail to connect to a board with Normal/System Reset
Try ConnectUnderReset / Hardware Reset connection
mode. This resets SWD connection in case it has been
disabled by application.
Refer to
Section 4.2 .
Fail to connect on board using
ConnectUnderReset/Hardware using ST-LINK Ensure NRST of ST-LINK is properly connected to MCU
NRST (e.g. check SB12 for Nucleo).
Fail to see clock signal on MCO output
Ensure that the clock configured to MCO is in the
supported range of the GPIO and that the OSPEED
setting is correct.
Refer to
Section 8.2 .
Impossible to evaluate a value or a variable, or
impossible to set a breakpoint at a specific line in code Compiler optimization is probably enabled. Remove it.
Refer to
Chapter 3: Compiling for debug .