Datasheet
78K0/Ix2 CHAPTER 25 FLASH MEMORY
R01UH0010EJ0500 Rev.5.00 657
Feb 28, 2012
25.4.7 On-board writing when connecting crystal/ceramic resonator
To write the flash memory on-board, connectors that connect the dedicated flash memory programmer must be
provided on the target system. First provide a function that selects the normal operation mode or flash memory
programming mode on the board.
When the flash memory programming mode is set, all the pins not used for programming the flash memory are in the
same status as immediately after reset. Therefore, if the external device does not recognize the state immediately after
reset, the pins must be processed as described below.
The state of the pins in the self programming mode is the same as that in the HALT mode.
When using the X1 (TOOLC0) and X2 (TOOLD0) pins as the serial interface for flash memory programming, signals
will collide if an external device is connected. To prevent the conflict of signals, isolate the connection with the external
device.
Similarly, when a capacitor is connected to the X1 and X2 pins, the waveform during communication is changed, and
thus communication may be disabled depending on the capacitor capacitance. Make sure to isolate the connection with
the capacitor during flash programming.
In cases when a crystal or ceramic resonator has been selected to generate the system clock, and the decision has
been made to execute on-board flash programming with the resonator mounted on the device because it is difficult to
isolate the resonator, be sure to thoroughly evaluate the flash memory programming with the resonator mounted on the
device
before executing the processing described next.
Mount the minimum-possible test pads between the device and the resonator, and connect the programmer via the
test pad. Keep the wiring as short as possible (refer to Figure 25-5 and Table 25-4).
Figure 25-5. Example of Mounting Test Pads
X1
(TOOLC0)
V
SS
Test pad
X2
(TOOLD0)
Table 25-4. Clock to Be Used and Mounting of Test Pads
Clock to Be Used Mounting of Test Pads
High-speed internal oscillation clock
External clock
Before resonator is mounted
Not required
Crystal/ceramic oscillation
clock
After resonator is mounted Required