Renesas RL78 Series Installation and operating instructions

Application Note
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RL78 Debugging Functions Using the Serial Port
Introduction
This application note describes how to use the RL78 debugging functions using the serial port.
Target Device
RL78
Contents
1. Overview .................................................................................................................................4
1.1 Overview of COM Port debugging...........................................................................................................4
1.2 Applicable devices...................................................................................................................................4
2. User system design.................................................................................................................5
2.1 Example of recommended connection between USB-to-serial conversion adapter and MCU...............5
2.1.1 General RL78 family connectivity..........................................................................................................5
2.2 Things to keep in mind when connecting................................................................................................6
2.2.1 RESET# pin...........................................................................................................................................6
2.2.2 TOOL0/TOOLTxD/TOOLRxD pins........................................................................................................8
2.2.3 GND.......................................................................................................................................................9
2.2.4 Power supply voltage ............................................................................................................................9
3. Usage notes..........................................................................................................................10
3.1 Power on/off ..........................................................................................................................................10
3.1.1 Power supply sequence ......................................................................................................................10
3.2 MCU resources that are used ...............................................................................................................11
3.2.1 Securing the debug monitor area........................................................................................................12
3.2.2 Securing the stack area for debugging ...............................................................................................13
3.2.3 Setting the on-chip debug option byte area ........................................................................................14
3.2.4 Setting the security ID .........................................................................................................................15
3.3 Reset .....................................................................................................................................................16
3.3.1 Behavior after reset.............................................................................................................................16
3.3.2 Registers after reset............................................................................................................................16
3.3.3 Pin reset during break .........................................................................................................................16
3.4 Flash memory........................................................................................................................................16
3.4.1 Debugging notes for self-programming...............................................................................................16
3.4.2 Voltage at which flash memory cannot be written and operation in flash operation mode.................17
3.5 GDIDIS function.....................................................................................................................................18
3.6 MCUs that are used in debugging.........................................................................................................18
3.6.1 Use in mass-production products........................................................................................................18

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3.6.2 Standalone operation check................................................................................................................18
3.7 Final evaluation of user program...........................................................................................................18
3.8 Debugging functions..............................................................................................................................19
3.8.1 “Go to Here” function ...........................................................................................................................19
3.8.2 Debugging in standby mode................................................................................................................19
3.8.3 Pseudo RRM/DMM functions..............................................................................................................20
3.8.4 Start/Stop functions.............................................................................................................................20
3.8.5 Emulation of flash memory CRC accumulator function ......................................................................20
3.8.6 Notes on the break function ................................................................................................................21
3.8.7 Setting and deleting events during user program execution...............................................................21
3.8.8 Trace function......................................................................................................................................21
3.8.9 Precautions when using flash read protection ....................................................................................21
3.9 How to improve debug performance.....................................................................................................22
Revision History............................................................................................................................23

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Definitions of Terms
The terms used in this document are defined and used as follows.
Host machine
A personal computer for controlling the emulator.
User system
The customer's application system using the MCU to be debugged.
User program
The application program to be debugged.
Flash writing software
In this document, this term refers to the Renesas Flash Programmer.
Meaning of “#” at the end of the pin name (signal name)
The # at the end of a pin name (signal name) indicates that it is a “Low” active pin (signal)
(example: RESET#).

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1. Overview
This guide presents the information you should be aware of when debugging RL78 devices with COM
Port debugging using a commercial USB-to-serial conversion adapter.
1.1 Overview of COM Port debugging
With the COM Port debugging system, you perform debugging by connecting to the target board from a
USB port of the host machine via a USB-to-serial conversion adapter instead of an emulator such as E2.
The adapter is recognized as the COM Port of the host machine when communicating with the target
device using the serial port.
It enables debugging of target devices using a commercially available USB-to-serial conversion adapter.
1.2 Applicable devices
Devices in the RL78 family that support COM Port debugging. Check the device's manual to see if it is
supported.
Table 1-1 List of debugging functions
Item
Support
Content
COM Port
E2 Lite
Reference/change memory during program execution
Pseudo real-time RAM monitor
(RRM)
Y*1
Y
CPU occupied during memory reference
Dynamic Memory Modification (DMM)
Y*1
Y
CPU occupied during memory changes
Event function
Up to
2points
Up to
2points
Can be used for hardware breaks
(or trace function*2)
Break
functions
Software breaks
Y
Y
Up to 2000 points
Hardware breaks
Y
Y
Execution address or data access
Forced breaks
Y
Y
-
Trace
functions
Acquired information
Y
Y
Branch source PC information
Start event
Y
Y
User program execution start, event start
End event
Y
Y
User program stop, event end, trace full
Execution time measurement function
N
Y
-
Hot plugin
N
Y
-
Coverage function
N
N
-
Y: supported, N: not supported
*1 RRM/DMM is possible on a per-variable basis, but it is recommended that the memory panel display
should be 1 or 2 lines and the update interval should be 5000 msec or more. If too much is displayed,
the debugger may become unresponsive.
*2 Only for devices with a trace function

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2. User system design
2.1 Example of recommended connection between USB-to-serial conversion
adapter and MCU
The recommended connection between the USB-to-serial conversion adapter and the MCU when using
COM Port debugging is shown below. For details on the processing of each signal line, refer to 2.2
Things to keep in mind when connecting.
2.1.1 General RL78 family connectivity
An example of connecting the USB-to-serial conversion adapter to the RL78 family is shown in Figure
2.1.
*CTS# is unused. Perform pin processing according to the specifications of the
serial conversion adapter you are using.
Figure 2.1 Example of connecting the USB-to-serial conversion adapter to the RL78 family

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2.2 Things to keep in mind when connecting
The pattern length between the USB-to-serial conversion adapter and the MCU should be as short as
possible (50 mm or less is recommended). Also, do not route signal lines on the board other than
between the USB-to-serial conversion adapter and the MCU.
For details on pin processing when COM Port debugging is not used, refer to the user's manual
(hardware edition) of the relevant MCU.
2.2.1 RESET# pin
The RESET# pin is used for resetting to the device.
An example of a connection to the RESET# pin area is shown in Figure 2.2.
When performing flash writing from the flash writing software, ensure that the reset signal on the user
system does not collide with the reset signal from the COM Port debugging.
Note that COM Port debugging does not support the RESET# pin masking function.
In addition, configure the debugger properties to match the pin (DTR/RTS) that controls the RESET# pin.
By default, the debugger/flash writing software uses DTR, so if you want to use RTS, be sure to change
the property settings.
The recommended connection is the DTR connection shown in Figure 2.2. If you are using a USB-to-
serial conversion adapter without DTR, use the RTS connection in Figure 2.3.
When using Printf debugging in the Arduino development environment, refer to Figure 2.4 when
connecting. Since RTS is fixed at LOW and the buffer output is disabled, RESET is pulled up externally.
Figure 2.2 RESET# pin connection example
(DTR connection)
Figure 2.3 RESET# pin connection example
(RTS connection)

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* The reference type name of the buffer connected to
DTR# is “74LVC1G126”.
OE control is as follows.
H: Enable output
L: Disable
Figure 2.4 RESET# pin connection example (with
buffer)
The following notes pertain to Figure 2.2, Figure 2.3, and Figure 2.4.
•Do not insert capacitors, additional series resistors, filters, etc. into the signal line as it may prevent normal
communication.
•The circuit and resistance values listed are recommended values and are not guaranteed.
Determine the circuit design and resistance values by taking into account the specifications and noise of the
target device.
•The reset circuit should be Nch.O.D output, and the pull-up in the reset circuit should be at least 10 kΩ or no pull-
up.

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2.2.2 TOOL0/TOOLTxD/TOOLRxD pins
The TOOL0/TOOLTxD/TOOLRxD pins are occupied and used when COM Port debugging is used.
Pin functions that are multiplexed to these pins cannot be used.
In addition, COM Port debugging uses the TOOLTxD/TOOLRxD pins to send and receive data to and
from the target device. Since mode entry is done using TOOL0, TOOL0 must be connected via the
TOOLRxD pin and resistor. No pull-up resistor is necessary.
When using COM Port debugging, do not set the port mode register dualed to TOOLRxD (PM1.1 when
TOOLRxD is a dual-use pin for P11) to 0 (output). If you do, the TOOLRxD pin, which is used in COM
Port debugging, will be in output mode and you will not be able to debug.
Figure 2.5 TOOL0/TOOLTxD/TOOLRxD pin connection example
Do not insert capacitors, additional series resistors, filters, etc. into the signal line as it may prevent normal
communication.

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2.2.3 GND
The GND of the USB-to-serial conversion adapter must be the same GND as the VSS pin of the MCU.
2.2.4 Power supply voltage
Use COM Port debugging at 1.8 V or higher, and stay within the operating voltage range of the USB-to-
serial conversion adapter. For debugging below 1.8 V, use E2.

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3. Usage notes
3.1 Power on/off
Follow the steps below to power the user system on and off.
3.1.1 Power supply sequence
[At the start of use]
(1) Confirm power is off
Make sure the user system is powered off.
(2) Connect user system
Connect the user system to the host machine.
(3) Start debugger or flash writing software
Start the debugger or flash writing software.
*If you are using VBUS supply as the system power supply, go to step (5).
(4) Power up user system
Turn on the power to the user system.
(5) Connect to user system from debugger or flash writing software through COM Port
The connection method varies depending on the software.
[At the end of use]
(1) Disconnect user system from debugger or flash writing software through COM Port
The disconnection method varies depending on the software.
*If you are using VBUS supply as the system power supply, go to step (3).
(2) Power off user system
Turn off the power to the user system.
(3) Exit debugger or flash writing software
Exit the debugger or flash writing software.
(4) Detach user system
Detach the user system from the host machine.