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IBM EM78P312N Bit Microcontroller, ADC Data Register, A/D Sampling Time, A/D Conversion Time

Models: EM78P312N

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ADC Data Register

EM78P312N

8-Bit Microcontroller

AD7 (P97)
AD6 (P96)
AD5 (P95)	8						VDD
	8						VREF
	to 1						VREF
AD4 (P94)	to 1
AD4 (P94)	Analog
						ADC	Power Down
				(Successive Approximation)			Start to Convert
AD3 (P93)	switch
AD2 (P92)
		Fosc/4
AD1 (P91)		Fosc/4	4 to 1
AD1 (P91)		Fosc/16	4 to 1
AD0 (P90)		Fosc/32	MUX
AD0 (P90)
7 - 0	2 1 0		5 4	5	5	9 8 7 6 5 4 3 2 1 0	6	3	7
ADIC	ADCR	ADCR		ISFR1		IMR1	ADCR
					DATA BUS

Fig. 5-5 AD Converter

It is a 10-bit successive approximation type AD converter. The upper side of analog reference voltage can select either internal VDD or external input pin P97 (VREF) by setting the ADREF bit in ADCR.

ADC Data Register

When the A/D conversion is completed, the result is loaded to the ADDH (8 bit) and ADDL (2 bit). The START/END bit is cleared, and the ADIF is set.

A/D Sampling Time

The accuracy, linearity, and speed of the successive approximation A/D converter are dependent on the properties of the ADC. The source impedance and the internal sampling impedance directly affect the time required to charge the sample holding capacitor. The application program controls the length of the sample time to meet the specified accuracy. Generally speaking, the program should wait for 2 μs for each KΩ of the analog source impedance and at least 2 μs for the low-impedance source. The maximum recommended impedance for the analog source is 10KΩ at VDD =5V. After the analog input channel is selected, this acquisition time must be done before A/D conversion can be started.

A/D Conversion Time

ADCK0 and ADCK1 select the conversion time (Tct), in terms of instruction cycles. This allows the MCU to run at maximum frequency without sacrificing accuracy of A/D conversion. For the EM78P312N, the conversion time per bit is about 4μs. Table 5 shows the relationship between Tct and the maximum operating frequencies.

Table 5

	ADCK1:0	Operation Mode		Max. Frequency		Max. Conversion		Max. Conversion
				(Fc)		Rate per Bit		Rate
	0 0	Fc/4		1MHz		250kHz (4μs)		48μs (20.8kHz)
	0 1	Fc/16		4MHz		250kHz (4μs)		48μs (20.8kHz)
	1 0	Fc/32		8MHz		250kHz (4μs)		48μs (20.8kHz)
	1 1	Reserved		-		-		-

Product Specification (V1.0) 10.03.2006								• 25

(This specification is subject to change without further notice)

Image 29

IBM EM78P312N manual Bit Microcontroller, ADC Data Register, A/D Sampling Time, A/D Conversion Time

Contents

EM78P312N Green Product Specification8-BIT Microcontroller ELAN MICROELECTRONICS CORPAll Rights Reserved ELAN MICROELECTRONICS CORPORATIONCopyright 2006 by ELAN Microelectronics Corporation Features ContentsGeneral Description Pin AssignmentAPPENDIX Specification Revision History1 General Description 2 FeaturesPin Assignment EM78P312NSymbol Pin DescriptionEM78P312N 8-Bit Microcontroller5 Function Description 5.1 Functional Block DiagramFig. 5-1 Functional Block Diagram This specification is subject to change without further noticeThis specification is subject to change without further notice 5.2 Operating RegistersEM78P312N 8-Bit Microcontroller8-Bit Microcontroller R0 Indirect Addressing Register EM78P312NR1 Time Clock /Counter R2 Program Counter & Stack8-Bit Microcontroller EM78P312NUser Memory Space R3 Status Register8-Bit Microcontroller EM78P312NBit 0 C Carry flag R4 RAM Select Register R5 System Control RegisterBit 7 ~ Bit 6 TC4FF1 ~ TC4FF0 Timer/Counter 4 flip-flop control RB Timer/Counter 4 Control RegisterEM78P312N 8-Bit Microcontroller R6 Port 6 I/O Data RegisterRC Timer 4 Data Buffer Bit 4 ~ Bit 2 TC4CK2 ~ TC4CK 0 Timer/Counter 4 Clock Source SelectEM78P312N 8-Bit MicrocontrollerRFInterrupt Status Flag Register EM78P312N8-Bit Microcontroller RE Interrupt Status Flag Register Bit 5 ~ Bit 4 TC3CK1 ~ TC3CK0 Timer/Counter 3 Clock Source Select Bank 1 R5 TC3CR Timer/Counter 3 Control RegisterTC3M = “1” Capture mode Bank 1 R6 TC3DA Timer 3 Data Buffer A Bank 1 R7 TC3DB Timer 3 Data Buffer BBank 1 R9 TC2DH Timer 2 Data Buffer High Byte Bit 2 ~ Bit 0 TC2CK2 ~ TC2CK0 Timer/Counter 2 Clock Source SelectBank 1 RA TC2DL Timer 2 Data Buffer Low Byte TC2M Timer/Counter 2 mode selectBit 7 ~ Bit 0 ADE7 ~ ADE0 AD input pin enable control ADP = “0” Power on ADP = “1” Power downEM78P312N 8-Bit MicrocontrollerTBTEN = “0” Disable TBTEN = “1” Enable TEN = “0” Disable TEN = “1” EnableBit 2 ~ Bit 0 TBTCK2 ~ TBTCK0 Time Base Timer Clock Source Select EM78P312NEM78P312N TXE = “0” Disable TXE = “1” Enable8-Bit Microcontroller Bit 4 ~ Bit 2 BRATE2 ~ BRATE1 Transmit Baud Rate SelectBit 0 RXE Enable receiving RXE = “0” Disable RXE = “1” Enable PRE = “0” Disable PRE = “1” Enable Bit 4 PRERR Parity error flagEM78P312N 8-Bit Microcontroller8-Bit Microcontroller EM78P312NBit 5 ~ Bit 3 BRS0 ~ BRS2 SPI Clock Source Select EDS = “0” Rising edge EDS = “1” Falling edge8-Bit Microcontroller EM78P312NBit 2 ~ Bit 1 SPIM1 ~ SPIM0 SPI Transfer Mode Select BankPHE7x = “0” Enable P7x pull high 5.3 Special Purpose RegistersPHE7x = “1” Disable P7x pull high WDTE = “0” Disable WDTE = “1” EnableEM78P312N Bit 6 INT0EN INT0 enable control INT0EN = “0” General I/O8-Bit Microcontroller Bit 2 PSR2 ~ Bit 0 PSR0 TCC prescaler bits IOC6 ~ IOC9 − I/O Port Control Register8-Bit Microcontroller EM78P312NADOSCR − AD Offset Control Register Address 0Ch Bit 5 ~ Bit 3 VOF2 ~ VOF0 Offset voltage bitsEM78P312N Bit 1 SPIE SPI Interrupt enable bit8-Bit Microcontroller IMR2 − Interrupt Mask Register 2 Address 0Fh8-Bit Microcontroller 5.4 CPU Operation ModeEM78P312N EM78P312N 5.5 AD Converter8-Bit Microcontroller Table 4. Wake-up Methods8-Bit Microcontroller EM78P312NADC Data Register A/D Sampling TimeFig. 5-6 Tone Output Pin Configuration 5.6 Time Base Timer and Keytone GeneratorFig. 5-7 Tone Output Pin Timing Chart EM78P312NFig. 5-9 Time Base Timer Timing Chart Fig. 5-8 TBT ConfigurationEM78P312N 8-Bit MicrocontrollerFig. 5-10 Function Block Diagram 5.7 UART Universal Asynchronous Receiver/TransmitterEM78P312N 8-Bit Microcontroller5.7.2 Transmitting 5.7.1 UART ModeEM78P312N 8-Bit Microcontroller5.7.4 Baud Rate Generator 5.7.3 ReceivingEM78P312N 8-Bit MicrocontrollerFig. 5-13 SPI Block Diagram 5.8 SPI Serial Peripheral InterfaceThis specification is subject to change without further notice EM78P312N5.8.1 Serial Clock 5.8.2 Shift Direction and Sample Phase5.8.3 Transfer Mode EM78P312Nc 8-bit Transmit/Receive Mode EM78P312N8-Bit Microcontroller b 8-bit Receive Mode 8-Bit Microcontroller EM78P312Nd Multiple Device Connect /SS SCK pinRegisters for Timer/Counter 2 Circuit 5.9 Timer/CounterFig. 5-18 Configuration of Timer/Counter EM78P312N5.9.2 Counter Mode 5.9.1 Timer Mode5.9.3 Window Mode EM78P312NRegisters for Timer/Counter 3 Circuit 5.10 Timer/CounterFig. 5-21 Window Mode Timing Chart EM78P312N5.10.2 Counter Mode 5.10.1 Timer Mode5.10.3 Capture Mode EM78P312N8-Bit Microcontroller 5.11 Timer/CounterEM78P312N 5.11.2 Counter Mode 5.11.1 Timer Mode5.11.3 PDO Mode EM78P312N5.11.4 PWM Mode 5.12 TCC/WDT & PrescalerEM78P312N 8-Bit Microcontroller5.14.1 Reset 5.14 Reset and Wake-up5.13 I/O Ports EM78P312N5.14.3 Wake-up from Idle Mode 5.14.2 Wake-up from Sleep ModeEM78P312N 8-Bit MicrocontrollerThis specification is subject to change without further notice Reset TypeEM78P312N 8-Bit MicrocontrollerThis specification is subject to change without further notice Reset TypeEM78P312N 8-Bit Microcontroller Register BankThis specification is subject to change without further notice Reset TypeEM78P312N 8-Bit Microcontroller Register BankReset Type Reset TypeThis specification is subject to change without further notice EM78P312N8-Bit Microcontroller General Purpose Registers 5.14.4 The Status of RST, T, and P of the Status RegisterEM78P312N 8-Bit Microcontroller 5.15 InterruptEM78P312N 5.16.1 Oscillator Modes 5.16 Oscillator5.16.2 Crystal Oscillator/Ceramic Resonators Crystal EM78P312N8-Bit Microcontroller EM78P312NOSCI XTALEM78P312N 5.16.3 External RC Oscillator Mode8-Bit Microcontroller Crystal/Resonator-Parallel Mode Circuit5.17.1 Code Option Register Word 5.17 Code Option RegisterENWDTB = “0” Enable ENWDTB = “1” Disable EM78P312N5.18.1 External Power-on Reset Circuit 5.18 Power-on Considerations5.17.2 Customer ID Register HLP = “0” Low power HLP = “1” High powerRESET 5.18.2 Residue-Voltage ProtectionEM78P312N 8-Bit Microcontroller8-Bit Microcontroller 5.19 Instruction SetEM78P312N 8-Bit Microcontroller EM78P312N6.1 Absolute Maximum Ratings 6 Absolute Maximum Ratings6.2 Recommended Operating Conditions EM78P312N7.1 DC Electrical Characteristics 7 Electrical CharacteristicsEM78P312N 8-Bit MicrocontrollerTa= 25 C, VDD= 3.0V ± 5%, VSS= EM78P312N8-Bit Microcontroller 8-Bit Microcontroller EM78P312NEM78P312N 7.2 AC Electrical Characteristic8-Bit Microcontroller Ta=- 40C ~ 85 C, VDD=5V ± 5%, VSS=0VRESET Timing CLK=0 7.3 Timing DiagramThis specification is subject to change without further notice EM78P312NEM78P312N APPENDIX A Package Types8-Bit Microcontroller OTP MCU