upd70f3402 Renesas Electronics Corporation., upd70f3402 Datasheet - Page 771

• Manufacturer Part Number: upd70f3402
• Description: 32-/16-bit Single-chip Microcontroller With Can Interface
• Manufacturer: Renesas Electronics Corporation.

22.3 Control Register
(1)
Notes: 1. On input to RESET pin (external reset): OCDM0 = 1
Symbol
OCDM
R/W
On-chip debug mode register (OCDM)
This register is used to select the normal operation mode or on-chip debug mode. This is a special
register (refer to 3.2.3 ”Special registers” on page 70). It can be written only in a specific
sequence so that its contents cannot be rewritten by mistake in the case of a program loop.
If the OCDM0 bit is 1 and if the DRST pin is high, the on-chip debug mode is selected.
The default value of the OCDM0 bit after the pin is reset is 1. It is therefore necessary to clear the
OCDM0 bit to 0 when the on-chip debug function is not used, and until then, the DRST pin must
be kept low (see Figure 22-4). The DRST pin is internally pulled down while the OCDM0 bit is 1,
and therefore, it may be left open.
After POC reset, the default value of the OCDM1 bit is 0, and the normal operation mode is
selected.
Therefore, it is necessary to set the OCDM0 bit to 1 by resetting the pin to use the on-chip debug
mode.
If POC reset occurs during on-chip debugging, communication with the emulator is disrupted.
Therefore, POC reset cannot be emulated (see Figure 22-5).
This register can be read or written in 8-bit or 1-bit units.
2. P97/SIB1/{DDI}
On reset by power-on clear: OCDM0 = 0
On occurrence of internal source reset (other than power-on clear): The OCDM register
holds the value before occurrence of reset.
P98/SOB1/{DCK
P99/SCKB1/{DMS}
P910/CS301/{DDO}
P911/{DRST}
OCDM0
R
7
0
0
1
Figure 22-2: On-Chip Debug Mode Register (OCDM) Format
R/W
Used as port/peripheral function pin
Used as on-chip debug pin
6
0
Specification of alternate-function pin of on-chip debug function
R/W
User’s Manual U16702EE3V2UD00
Chapter 22 On-Chip Debug Function
5
0
R/W
4
0
R
3
0
R
2
0
R
1
0
OCDM0 FFFFF9FCH
R/W
0
Address
Note 2
After reset
01H
Note 1
771