ELAN Home Systems EM78P459AK, EM78P459AM, EM78P458AM, EM78P458AP manual External RC Oscillator Mode

Page 48

EM78P458/459

OTP ROM

3. External RC Oscillator Mode

For some applications that do not require precise timing calculation, the RC oscillator (Fig. 22) could offer users with an effective cost savings. Nevertheless, it should be noted that the frequency of the RC oscillator is influenced by the supply voltage, the values of the resistor (Rext), the capacitor(Cext), and even by the operation temperature. Moreover, the frequency also changes slightly from one chip to another due to the manufacturing process variation.

In order to maintain a stable system frequency, the values of the Cext should not be less than 20pF, and that the value of Rext should not be greater than 1M ohm. If they cannot be kept in this range, the frequency can be affected easily by noise, humidity, and leakage.

The smaller the Rext in the RC oscillator, the faster its frequency will be. On the contrary, for very low Rext values, for instance, 1 KΩ, the oscillator becomes unstable because the NMOS cannot discharge the current of the capacitance correctly.

Based on the above reasons, it must be kept in mind that all supply voltage, the operation temperature, the components of the RC oscillator, the package types, and the way the PCB is layout, have certain effect on the system frequency.

OSCI

EM78P458

EM78P459

Vcc

Rext

Cext

 

 

Fig. 22

Circuit for External RC Oscillator Mode

Table 14 RC Oscillator Frequencies

 

 

 

 

 

 

 

 

 

 

 

Cext

Rext

 

Average Fosc 5V,25°C

Average Fosc 3V,25°C

 

 

 

 

 

 

 

 

 

3.3k

 

3.57 MHz

2.94 MHz

 

 

20 pF

5.1k

 

2.63MHz

1.92 MHz

 

 

10k

 

1.30 MHz

1.22 MHz

 

 

 

 

 

 

 

100k

 

150 KHz

153 KHz

 

 

 

 

This specification is subject to change without prior notice.

48

07.01.2003 (V1.3)

Page 47 Page 49
Image 48
Page 47 Page 49
Contents EM78P458/459 BIT MICRO-CONTROLLEREM78P458/459 Application NoteGeneral Description Features EM78P458/459 PIN Assignment EM78P459 Pin Description Function Description Operational RegistersR0 Indirect Addressing Register R1 Time Clock /CounterProgram Counter Organization R3 Status Register R4 RAM Select RegisterR5 ~ R6 Port 5 ~ Port R7 ~ R8Data Memory Configuration R9 Adcon Analog to Digital Control RA Addata the converted value of ADC10. RB 11. RCSpecial Purpose Registers 13. RERF Interrupt Status Register 15. R10 ~ R3FControl Register IOC50 ~ IOC60 I/O Port Control RegisterInte INT PAB PSR2 PSR1 PSR0 Bit 0 PSR0 ~ Bit 2 PSR2 TCC/WDT prescaler bitsIOC90 Gcon I/O Configuration & Control of ADC OP2E OP1EVrefs COE IMS2 IMS1 IMS0 CKR1 CKR0 Description of AD Configuration Control Bits IOCB0 Pull-down Control RegisterBit4Bit2 IMS2IMS0 IMS2IMS0IOCC0 Open-Drain Control Register IOCD0 Pull-high Control RegisterIOCE0 WDT Control Register IOCF0 Interrupt Mask RegisterWdte EIS Cmpie PWM2IE PWM1IE Adie Exie Icie TcieIOC51 Pwmcon PWM2E PWM1E T2EN T1ENIOC81 PRD1 Period of PWM1 CALI1 SIGN1Bit 5Bit 3 VOF12VOF10 Offset voltage bits CALI2 SIGN2IOCB1 PRD2 Period of PWM2 Bit 5Bit 3 VOF22VOF20 Offset voltage bitsTCC/WDT & Prescaler Block Diagram of TCC and WDT I/O PortsCcircuit of I/O Port and I/O Control Register for Port Circuit of I/O Port and I/O Control Register for P60~P67 Reset and Wake-up Function of Reset and Wake-upUsage of Port 6 Input Changed Wake-up/Interrupt Function Contw CLR R1 Status of T, and P of Status Register Values of RST, T, and P after Reset Status of RST, T and P being Affected by EventsInterrupt Analog-To-Digital Converter ADC Interrupt Input CircuitBIT Symbol Iocs Adrun Adpd ADIS2 ADIS1 ADIS0 BIT Symbol Vrefs COE IMS2 IMS1 IMS0 CKR1 CKR0ADC Control Register ADCON/R9, AD-CMP-CON/IOCA0, GCON/IOC90 ADCON/R9ADC Data Register ADDATA/RA CKR1 and CKR0 Bit 1 and Bit 0 The conversion time selectGCON/IOC90 Shows the Gains and the Operating Range of ADCD Operation During Sleep Mode D Sampling TimeD Conversion Time Programming Steps/ConsiderationsDemonstration Programs CINT== 0XFIocs Adrun Adpd ADIS2 ADIS1 ADIS0 Dual Sets of PWM Pulse Width Modulation OverviewIncrement Timer Counter Tmrx TMR1H/TWR1L or TMR2H/TWR2L Functional Block Diagram of the Dual PWMsPWM Programming Procedures/Steps PWM Period Prdx PRD1 or PRD2Comparator Period = Prdx + 1 * 4 * 1/Fosc * Tmrx prescale valueTimer Function descriptionTMR1X and TMR2X TMR1H/TWR1L and TMR2H/TMR2L Prdx PRD1 and PRD2 PWM period registerTimer programming procedures/steps External Reference SignalComparator Programming the Related RegistersUsing as An Operation Amplifier Wake-up from Sleep ModeInterrupt Initialized Values after Reset Summary of the Initialized Values for RegistersCALI1 SIGN1 Oscillator Oscillator ModesCrystal Oscillator/Ceramic Resonators Xtal Summary of Maximum Operating SpeedsEM78P458 EM78P459HXT LXTEM78P458 EM78P459 VddExternal RC Oscillator Mode RC Oscillator Mode with Internal Capacitor EM78P458 EM78P459 Vcc RextPower-on Considerations External Power on Reset CircuitResidue-Voltage Protection EM78P458 EM78P459 RinCode Option Register Word Enwdt Clks PTB HLF RCT HLPBit 5 ~ Bit 0 ID5~ID0 Customer’s ID Bit 11 ~ Bit 9 VOF22~VOF20 Offset voltage bitsInstruction Set List of the instruction set of EM78P458/459ADD A,R Timing Diagrams Reset Timing CLK=0AC Test Input/Output Waveform TCC Input Timing CLKS=0Absolute Maximum Ratings Electrical Characteristics Crystal type, two clocksComparatorOP CharacteristicVdd = 5.0V,Vss=0V,Ta=0 to AC Electrical CharacteristicTa=0C ~ 70 C, VDD=5V±5%, VSS=0VIVR Appendix Package TypesOTP MCU DIP

EM78P458, EM78P459AM, EM78P458AM, EM78P459AK, EM78P459 specifications

ELAN Home Systems offers a range of advanced microcontrollers, including the EM78P458AP, EM78P459, EM78P459AK, EM78P458AM, and EM78P459AM, that cater to various applications in the consumer electronics sector. These microcontrollers are known for their high efficiency, low power consumption, and robust performance, making them ideal for a wide range of smart home devices.

The EM78P458AP and EM78P459 models feature an 8-bit architecture, enabling efficient processing for applications requiring moderate complexity. They are equipped with a variety of I/O options, including GPIO, UART, and ADC, facilitating seamless integration with numerous peripherals. This flexibility allows developers to create customized solutions tailored to specific user needs.

One of the main highlights of these microcontrollers is their low-power operation, which is essential for battery-operated devices. This is particularly appealing in smart home contexts, where devices are expected to maintain long operational lifetimes without frequent battery replacements. The EM78P458AP and EM78P459 series prioritize energy efficiency, ensuring that they consume minimal power during both active and idle states.

In terms of memory, these microcontrollers also provide substantial ROM and RAM capacities, which enhance their ability to handle complex programs and data. The EM78P459AK variant adds additional features that empower developers with greater flexibility in terms of code storage and execution.

Another critical aspect of these microcontrollers is their built-in protection mechanisms, including voltage and thermal protection, which ensure safe operations under varying environmental conditions. This is vital for home automation systems, where device reliability is paramount to user satisfaction.

The EM78P458AM and EM78P459AM models further extend the family with added functionalities, such as enhanced communication capabilities featuring protocols like I2C and SPI. This facilitates robust inter-device communication, making it easier to integrate various smart home devices into a cohesive network.

Overall, ELAN Home Systems’ EM78P458 and EM78P459 series microcontrollers stand out for their versatile application potential, low power consumption, and reliability. With their innovative technologies and characteristics, they are well-suited for driving the next generation of smart home solutions, ensuring convenience, efficiency, and connectivity for users worldwide.
Top Page Image Contents