
User’s Manual U19780EJ2V0UD
612
CHAPTER 26 ON-CHIP DEBUG FUNCTION
26.1 Connecting QB-MINI2 to 78K0/Kx2-A microcontrollers
The 78K0/Kx2-A microcontrollers use the V
DD
, FLMD0, RESET, OCD0A/X1 (or OCD1A/P31), OCD0B/X2 (or
OCD1B/P32), and V
SS
pins to communicate with the host machine via an on-chip debug emulator (QB-MINI2).
Whether OCD0A/X1 and OCD1A/P31, or OCD0B/X2 and OCD1B/P32 are used can be selected.
Caution The 78K0/Kx2-A microcontrollers have an on-chip debug function, which is provided for
development and evaluation. Do not use the on-chip debug function in products designated for
mass production, because the guaranteed number of rewritable times of the flash memory may
be exceeded when this function is used, and product reliability therefore cannot be guaranteed.
NEC Electronics is not liable for problems occurring when the on-chip debug function is used.
Figure 26-1. Connection Example of QB-MINI2 and 78K0/Kx2-A microcontrollers
(When OCD0A/X1 and OCD0B/X2 Are Used)
V
DD
Target device
P31
FLMD0
X1/OCD0A
X2/OCD0B
Reset signal
RESET_IN
Note 1
DATA
CLK
FLMD0
RESET
V
DD
RESET_OUT
GND
Target connector
(10-pin)
GND
Note 2
V
DD
Reset circuit
V
DD
V
DD
GND
R.F.U.
R.F.U.
Note 2
10 k
Ω
(Recommended)
1 k
Ω
(Recommended)
(Open)
(Open)
Notes 1.
This connection is designed assuming that the reset signal is output from the N-ch open-drain buffer
(output resistance: 100
Ω
or less). For details, refer to
QB-MINI2 User’s Manual (U18371E)
.
2.
Make pull-down resistor 470
Ω
or more (10 k
Ω
: recommended).
Cautions 1. Input the clock from the OCD0A/X1 pin during on-chip debugging.
2. Control the OCD0A/X1 and OCD0B/X2 pins by externally pulling down the OCD1A/P31 pin or
by using an external circuit using the P130 pin (that outputs a low level when the device is
reset).