Renesas Electronics Europe GmbH A © 2010 Renesas Electronics Corporation. All rights reserved. RL78 Clock Generator

© 2010 Renesas Electronics Corporation. All rights reserved. 2 Purpose This course provides an introduction to the RL78 clock generator. Different oscillator and operation modes will be explained. Finally the new Snooze mode will be explained. Objectives Learn about the functions RL78 clock generator. Understand the different int. and ext. oscillators Understand the Snooze mode capabilities. Content 23 pages (including this page) Learning Time = 30 minutes Introduction

© 2010 Renesas Electronics Corporation. All rights reserved Bit CPU core Operates up to 32MHz clock oscillation V DD = 2.7V-5.5V) Operates up to 4MHz clock oscillation V DD = 1.6V-5.5V) Minimum instruction cycle time 32MHz Wide operating voltage range V DD = 1.6V-5.5V High-speed on-chip oscillator (1,2,3,4,6,8,12,16,24,32 MHz) On-chip voltage regulator (2.1V) leads to low current consumption and low EMI Internal voltage regulator

© 2010 Renesas Electronics Corporation. All rights reserved. 4 Up to four different oscillators Main system clock oscillator up to 20MHz Internal selectable on-chip oscillator 1 to 32MHz –Reduces power consumption –Best speed / I DD relation Internal “low speed” on-chip oscillator 15kHz Subsystem clock oscillator (32.768kHz) (if available) CPU core operation on all clocks possible (except “15kHz” on-chip osc.) Clock generator

© 2010 Renesas Electronics Corporation. All rights reserved. 5 Example for RL78/G13 64 pin Oscillator terminals can be used as ports, if no external oscillator is connected. Clock generator (cont.) CPU Watchdog Timer Peripherals Int. Oscillator 15 kHz ± 15 % Int. Oscillator 15 kHz ± 15 % Selector Ext.Oscillator kHz Ext.Oscillator kHz Int. Oscillator 24,32 MHz ± 1% Int. Oscillator 24,32 MHz ± 1% Ext. Oscillator 1…20 MHz Ext. Oscillator 1…20 MHz Interval Timer RTC Interval Timer RTC

© 2010 Renesas Electronics Corporation. All rights reserved. 6 Block Diagram Clock generator

© 2010 Renesas Electronics Corporation. All rights reserved. 7 +/- 1% accuracy over voltage and temperature Note1 Two pre-set frequencies: 24 MHz and 32MHz Note 2 Improved accuracy with correction register Down to 0.05 Note 1: Target for RL78/G13 Note 2: RL78/G13 % Accuracy Vcc (V) Typical MCU RL Temp (C) 24 or 32 MHz +/- 1 % Factory Guaranteed! Internal oscillators

© 2010 Renesas Electronics Corporation. All rights reserved. 8 Clock dividing Select 24MHz or 32MHz frequency by bit 3 of option-byte(00C2H).after reset. Bit 2 to bit 0 are transferred to HOCODIV then dividing rate of source frequency is decided. This makes a clock of 32MHz to 1MHz. Software can change HOCODIV that transferred value of option byte. Selection of 32MHz or 24MHz Transfer to HOCODIV after reset. It is possible to rewrite dividing rate by software.

© 2010 Renesas Electronics Corporation. All rights reserved. 9 “High Speed main” mode “Low Speed main” mode 32KHz operation 32KHz RUN 32KHz/2 RUN 32KHz HALT + RTC 0.7uA with RTC Typical power consumption Power consumption values with code execution from Flash

© 2010 Renesas Electronics Corporation. All rights reserved to 20MHz oscillation speed Supports external quartz, resonator or external clock signal Can be selected by software After reset the device starts always with the internal high speed osc. Oscillator terminals can be used as ports, if no external oscillator is connected. External oscillator

© 2010 Renesas Electronics Corporation. All rights reserved. 11 Start-Up behaviour of the oscillators ItemTyp.MaxUnit Startup time of HOCO including reset processing Us Automatically started by reset Started by software if necessary Oscillator startup

© 2010 Renesas Electronics Corporation. All rights reserved. 12 Clock generator initialisation Startup behavior in case ext. Oscillator is used void OscInit(void)// Clock generator initialization { CMC = 0x51;// Set up the operation mode of the X1/P121, X2/EXCLK/P122, // XT1/P123, and XT2/P124 pins can be written only once!! OSTS = 0x07;// Select the required oscillator stabilization time CKC = 0x00;// Select the CPU and the peripheral hardware clock. MSTOP = 0;// Enable X1 input clock operation while (OSTC < 0xFF)// Wait until X1 input clock stabilization time has been changed { __no_operation(); } do {// Switch CPU clock to fX1 input clock and MCM0 = 1;// check, if CPU is operating on fX1 input clock }// If not, switch CPU clock again to fX1 input clock and check again while (MCS != 1); // HIOSTOP = 1;// Switch off the high-speed on-chip oscillator and // XTSTOP = 1;// the subclock if not needed PER0 = 0xFF;// Switch on the peripheral clock supply PER1 = 0x01; }

© 2010 Renesas Electronics Corporation. All rights reserved. 13 Definition of instruction cycle time One instruction clock cycle (T CYCL ) is one cycle of the CPU clock (f CPU ) selected by the system clock control register (CKC). Example: –f X = 32MHz, CKC = 0x10 => f CPU = 32MHz => T CYCL = 1 / f CPU = 31.25ns –e.g. MOV r, #Byte : T INST = 1 clock * T CYCL => T INST = 1 * 31.25ns = 31.25ns Instruction time

© 2010 Renesas Electronics Corporation. All rights reserved. 14 Minimum instruction cycle time vs. supply voltage “Low voltage main” mode Vdd [V] Frequency [MHz] “Low Speed main” mode “High Speed main” mode Mode select by Flash “Option byte” Operating range

© 2010 Renesas Electronics Corporation. All rights reserved. 15 Main system clock and high-speed on-chip oscillator Halt mode –Oscillator is operating, CPU core is stopped, peripherals are active –Halt mode release possible with interrupts or reset Stop mode –Oscillator is stopped, CPU core is stopped, peripherals are not active –Stop mode release possible with external interrupts or reset or internal interrupts by internal low speed osc. Or sub- system-clock operated peripherals. Snooze mode (internal high-speed oscillator) –CSI00 or UART0 data reception possible –Timer triggered A/D-conversion Possible chip operation modes

© 2010 Renesas Electronics Corporation. All rights reserved kHz on-chip oscillator Only the watchdog timer, interval timer and RTC can operate with the low-speed on-chip oscillator Subsystem clock Operation mode –CPU core and peripherals are using subsystem clock Halt mode –CPU core is stopped, peripherals are using subsystem clock –Halt mode release possible with external interrupts, reset, peripherals supplied by subsystem clock or watchdog timer Possible chip operation modes (cont.)

© 2010 Renesas Electronics Corporation. All rights reserved. 17 Operation mode transitions Mode transitions: HALT Instruction STOP Instruction HALT Instruction Release by ext. interrupt interrupt from wake up timer reset Release by ext. interrupt int. interrupt reset RESET Release by valid serial reception AD value match Release by reception detection timed AD trigger Release by no valid reception no AD value match SNOOZE CPU Clock Peripheral STOP CPU ClockPeripheral HALT CPU ClockPeripheral RUN CPU ClockPeripheral Peripheral; DMA, etc operation is possible Reduce current consumption below HALT mode Release by valid serial reception AD value match NEW

© 2010 Renesas Electronics Corporation. All rights reserved. 18 Benefits of snooze mode What is the new „SNOOZE“ mode MAIN RUN HALT STOP SNOOZE SUB HALT SUB RUN <- Keep lowest power - current consumption between STOP & HALT mode Receive & check UART & CSI without active CPU Convert & check AD conversion without active CPU SNOOZE MODE advantages SNOOZE Set the CPU into STOP mode and… … Receive & check Serial Data … Convert & check conversion result without usage of the CPU Set the CPU into STOP mode and… … Receive & check Serial Data … Convert & check conversion result without usage of the CPU Snooze mode is something in between STOP and the RUN mod Snooze mode is something in between STOP and the RUN mod

© 2010 Renesas Electronics Corporation. All rights reserved. 19 ADC operation during standby state Four comparison criteria: Within/Outside Window, Higher/Lower than Limit Over 60% reduction in power consumption vs. to standard ADC operation Low Power: Snooze Mode (ADC)

© 2010 Renesas Electronics Corporation. All rights reserved. 20 Serial interface operation during standby state Wake up from SNOOZE by valid reception Low Power: Snooze Mode (serial interface)

© 2010 Renesas Electronics Corporation. All rights reserved. 21 In this course, we learned about: Functions RL78 clock generator. Different int. and ext. oscillators Operating Modes Snooze mode capabilities. Thanks for viewing! For More information on Renesas Products, visit Summary

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