Debug support (DBG) RM0444
1368/1390 RM0444 Rev 5
Refer to the Cortex
®
-M0+ TRM for a detailed description of DPACC and APACC registers.
The packet request is always followed by the turnaround time (default 1 bit) where neither
the host nor target drive the line.
The ACK Response must be followed by a turnaround time only if it is a READ transaction
or if a WAIT or FAULT acknowledge has been received.
The DATA transfer must be followed by a turnaround time only if it is a READ transaction.
40.5.3 SW-DP state machine (reset, idle states, ID code)
The State Machine of the SW-DP has an internal ID code which identifies the SW-DP. It
follows the JEP-106 standard. This ID code is the default Arm one and is set to
0x0BB11477 (corresponding to Cortex
®
-M0+).
Table 248. Packet request (8-bits)
Bit Name Description
0 Start Must be “1”
1 APnDP
0: DP Access
1: AP Access
2RnW
0: Write Request
1: Read Request
4:3 A[3:2]
Address field of the DP or AP registers (refer to Table 252 on
page 1370)
5 Parity Single bit parity of preceding bits
6Stop 0
7Park
Not driven by the host. Must be read as “1” by the target
because of the pull-up
Table 249. ACK response (3 bits)
Bit Name Description
0..2
ACK
001: FAULT
010: WAIT
100: OK
Table 250. DATA transfer (33 bits)
Bit Name Description
0..31
WDATA or
RDATA
Write or Read data
32
Parity
Single parity of the 32 data bits
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