45
Pin Functions
Chapter 2
Preliminary User’s Manual U17566EE1V2UM00
(5)
OCDM - On-chip debug mode register
The 8-bit OCDM register specifies whether dedicated pins of the
microcontroller operate in normal operation mode or can be used for on-chip
debugging (N-Wire interface). The setting of this register concerns only those
pins that can be used for the N-Wire interface: P05/DRST, P52/DDI, P53/DDO,
P54/DCK, and P55/DMS.
To make these pins available for on-chip debugging, bit OCDM.OCDM0 must
be set while pin DRST is high. If the on-chip debug mode is selected, the
corresponding pins are automatically set as input or output pins, respectively.
Setting of bits PMn.PMnm is not necessary.
For more details refer to
“On-Chip Debug Unit“ on page 877
.
Access
This register can be read/written in 8-bit and 1-bit units.
Address
FFFF F9FC
H
Initial Value
00
H
/01
H
:
• After Power-On Clear reset, the normal operation mode is selected
(OCDM.OCDM0 = 0).
• After external reset, the dedicated pins are available for on-chip debugging
(OCDM.OCDM0 = 1).
• After any other reset, bit OCDM0 holds the same value as before the reset.
Note
If the pins P05/DRST, P52/DDI, P53/DDO, P54/DCK, and P55/DMS are used
as N-Wire interface pins their configuration can not be changed by the pin
configuration registers.
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
OCDM0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Table 2-8
OCDM register contents
Bit position
Bit name
Function
0
OCDM0
Enables/disables N-Wire interface:
0: Pins are used in normal operation mode (port
mode or alternative mode).
1: Pins are used in on-chip debug mode.
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