White Paper – New functions of the RL78/G23 Logic and Event Link Controller (ELCL) Page 1 of 16
White Paper
New functions of the RL78/G23
Logic and Event Link Controller (ELCL)
Sho Hataki, MCU Product Marketing Department, MCU Device Solution Business Division, IoT and Infrastructure
Business Unit, Renesas Electronics Corporation.
July. 2021
Introduction
Logic and Event link controller (ELCL) of the RL78/G23 is added some logic control circuits for Event link
controller (ELC) function of RL78/G14 and others. ELC events of some peripheral functions can be linked
the other peripheral functions without CPU. New logic circuits are AND, OR, flip-flops and other circuits,
therefore when using event link peripheral to the other peripherals, various combinations can be realized
without an external circuit and without CPU load. And you can also add new functions to the
microcontroller.
This white paper provides some overviews of ELCL, how to use it, and its applications.
What is Logic and Event link controller (ELCL)
Explanation the features of ELCL
⚫ Event link controller (ELC) function
ELC function of RL78/G14 and others links event signals output by peripheral functions to other
specified peripheral functions through internal circuits directly. ELCL can be used as ELC
function.
This function is allowing direct communications between peripheral functions without CPU
intervention. Therefore, when an event occurs, peripheral functions can be started in short time.
And it realizes low power when microcomputer is standby mode, because CPU can be kept
standby mode.
White Paper – New functions of the RL78/G23 Logic and Event Link Controller (ELCL) Page 2 of 16
Event
occurred
Standby
CPU
operation
Linking events with ELCL eliminates the need for standby release
Enables low power consumption
Events
External interrupt
Timer interrupt
Key Interrupt
ELCL
Peripheral
functions
Timer
ADC
DAC
Interrupt
Controller
CPU
タイマ割り込み
ELCL
Interrupt
Controller
CPU
Stop
Direct response Starts even when CPU is stopped
ADC
conversion
Standby
Interrupt
Event
occurred
Standby
ADC
conversion
Standby
ELCL
Linking events with ELCL eliminates the need for interrupt processing
Enables fast startup of peripheral functions
Interrupt
ELCL
RET instruction/PC evacuation Interrupt processing
Link process Time saving
Number of cycles
Events
External interrupt
Timer interrupt
Key Interrupt
Peripheral
functions
Timer
ADC
DAC
Figure 1. ELC function
⚫ Logic functions
ELCL provides additional logic functions to the traditional ELC functions.
The logic function can link the event signals of each peripheral function via the logic circuit such
as AND, OR, EX-OR, flip-flop circuits. With this feature can link not only simple combination link
but also many combinations with various conditions.
PORT
Timer
Serial
CMP
Clock
Interrupt
SEL
D Q
R
SEL
SEL
SEL
PORT
Timer
Serial
Various
triggers
SEL
SEL
Input signal
selector
Event controller
(link processor)
Output signal
selector
Logic and event link controller (ELCL)
SEL
Figure 2. Logic function