Cautions On Target System Design - Renesas QB-MINI2 User Manual

4.1.4

Cautions on target system design

Note the following cautions when designing the target system.
<R> • If possible, do not create sections in which the communication lines for debugging (OCDxA, OCDxB, TOOLCx,
and TOOLDx) run in parallel in the target system. If this cannot be prevented, shorten the sections as much as
possible.
oscillation, be sure to make the section where TOOLC0 and TOOLD0 run in parallel less than 30 mm.
<R> • Use a GND pattern to shield the communication lines for debugging (OCDxA, OCDxB, TOOLCx, and TOOLDx)
to reduce their capacitive load, because the lines are used for high-speed communication.
• Make the distance between the target connector and the target device as short as possible.
• Before shipping the product, use jumpers or other means to physically separate the X1 and X2 pins from the
target connector in order to ensure normal clock oscillation.
<R> • To use OCD0A, OCD0B, TOOLC0, and TOOLD0 as communication pins for debugging, remove elements such
as resonator capacitance and feedback resistors, so that the signals do not degrade due to capacitive load.
CHAPTER 4 HOW TO USE MINICUBE2 WITH 78K0 MICROCONTROLLER
When using TOOLC0 and TOOLD0 as communication lines for debugging by using X1 or X2
Figure 4-22. Reference Diagram of Target System
Target device Target device
X1 X1 X2 X2
GND pattern GND pattern
Make the pattern where X1 and X2 are Make the pattern where X1 and X2 are
next to each other as short as possible, or next to each other as short as possible, or
make the space wider make the space wider
Connect to the connector by using Connect to the connector by using
tin plating when debugging tin plating when debugging
User's Manual U18371EJ5V0UM
Shield both sides of the line to Shield both sides of the line to
reduce noise reduce noise
To debug To debug
connector connector
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