SPRUJF2A March 2026 – March 2026 AM13E23019
Debug connections to the device are also supported through an Arm Serial Wire Debug (SWD) compliant interface known as the SW-DP. The SW-DP interface requires two connections:
The SWD interface uses the standard logic levels of the device for SWD communication. See the device-specific data sheet for input and output logic levels for a given supply voltage (VDD). A SWCLK frequency of up to 40MHz is supported by the DEBUGSS.
During SWD operation, the SWDIO line can be driven high or driven low by either the target device or the debug probe. As either device can drive the line, when ownership of the shared SWDIO line is switched between the device and the debug probe, undriven time slots are inserted as a part of the SWD protocol. The primary purpose of the pullup resistor on the SWDIO line, and the pulldown resistor on the SWCLK line, is to place the SWD pins into a known state when no debug probe is attached. A minimum resistance of 100kΩ is recommended by Arm. The internal pullup/pulldown resistors fulfill this requirement and external resistors are not required for correct operation of the SWD interface.
After a power-on reset (POR), AM13E230x devices configure the SWD pins in SWD mode with an internal pullup resistor enabled on the SWDIO line and an internal pulldown resistor enabled on the SWCLK line. If the device configuration has not permanently disabled all SWD access, then the SWD interface is enabled during the boot process and a debug probe can be connected to the DEBUGSS.
Upon physical connection of a debug probe, a valid JTAG-to-SWD sequence must be sent from the debug probe to the SWJ-DP on SWDIOTMS to initiate a SWD connection with the SW-DP. Once the sequence is applied and the SWD connection is established, communication with enabled debug access points is possible.