Hyundai GMS90X51C Serial Interface Usart, Usart Operating Modes, Baudrate Description, SM0 SM1

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HYUNDAI MicroElectronics

GMS90X5XC Series

SERIAL INTERFACE (USART)

The serial port is full duplex and can operate in four modes (one synchronous mode, three asynchronous modes) as illustrated in Table 6. The possible baud rates can be calculated using the formulas given in Table 7.

Table 6. USART Operating Modes

	Mode	SCON		Baudrate		Description

		SM0	SM1
		SM0	SM1
	0	0	0	fOSC		Serial data enters and exits through RxD.
	0	0	0	------------		Serial data enters and exits through RxD.
				12		TxD outputs the shift clock. 8-bit are transmit-
						TxD outputs the shift clock. 8-bit are transmit-
						ted/received (LSB first)

	1	0	1	Timer 1/2 overflow rate		8-bit UART
						10 bits are transmitted (through TxD) or
				fOSC	fOSC	received (RxD)
	2	1	0	fOSC	fOSC	9-bit UART
	2	1	0	------------ or	------------	9-bit UART
				32	64	11 bits are transmitted (TxD) or received (RxD)
						11 bits are transmitted (TxD) or received (RxD)

	3	1	1	Timer 1/2 overflow rate		9-bit UART
						Like mode 2 except the variable baud rate

Table 7. Formulas for Calculating Baud rates

	Baud Rate	Interface Mode				Baudrate
	derived from	Interface Mode				Baudrate
	derived from
	Oscillator	0				fOSC
	Oscillator	0				----12--------
						----12--------
		2		2SMOD			× fOSC
		2	2SMOD-------			64----------	× fOSC
			2SMOD-------			64----------
	Timer 1 (16-bit timer)	1,3	2---SMOD--32------------ × (Timer 1 overflow)
	(8-bit timer with	1,3	2---SMOD--32------------ × (Timer 1 overflow)
	8-bit auto reload)	1,3	------	-32----------	---------------12× [-256-----------–-----(--TH1-------------)---]
	Timer 2	1,3				fOSC
	Timer 2	1,3	32-------------------------------------------× [65536 – (RC2H----------------,---RC2L----------------)---]

20	Jan. 2001 Ver 1.0

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Contents GMS90X51C GMS90X52C GMS90X54C Page Mask Block Diagram GMS90C51CGMS90C52C/54C GMS90L52C/54CLow voltage versions PIN Configuration Plcc Pin Configuration top viewPdip Pin Configuration top view EA / VPP ALE / ProgMqfp Pin Configuration top view Logic Symbol PIN Definitions and Functions XTAL2Symbol Function Program Store EnableReset Pin NumberAddress Latch Enable Circuit ground potentialNo connection Block Diagram of the GMS90X5XC series Functional DescriptionCPU Special Function Register PSWSpecial Function Registers C0H D0HFFH D8H E0HContents of SFRs, SFRs in Numeric Order Address Register E0HF0H D0HGF1 GF0 PDE Idle C8H T2CON TF2 EXF2 Rclk Tclk EXEN2 TR2 CP/RL2 X2 Mode Clock Generation DiagramMode Swithcing Waveforms Timer / Counter 0 Timer/Counter 0 and 1 Operating Modes DescriptionTmod Input ClockTimer Timer/Counter 2 Operating ModesP1.1 Remarks Input Clock T2EXSerial Interface Usart Usart Operating ModesBaudrate Description SM0 SM1Interrupt System Interrupt Request SourcesInterrupt Priority-Within-Level Interrupt Source Power Saving Modes Electrical Characteristics Absolute Maximum RatingsDC Characteristics for GMS90C51C/52C/54C Parameter Symbol Limit Values Unit Test Conditions MinPower supply current Hyundai MicroElectronics DC Characteristics for GMS90L51C/52C/54C VCC= 3.3V + 0.3V, -0.6V VSS=0V TA= 0C to 70CExplanation of the AC Symbols AC Characteristics for GMS90X5XC series 12MHz versionExternal Program Memory Characteristics GMS90X5XC Series Advance Information 12MHz External Clock Drive AC Characteristics for GMS90X5XC series 16MHz version Advance Information 16MHz External Clock Drive AC Characteristics for GMS90X5XC series 24MHz version Advance Information 24MHz External Clock Drive AC Characteristics for GMS90X5XC series 33MHz version Advance Information 33MHz External Clock Drive AC Characteristics for GMS90X5XC series 40MHz version Advance Information 40MHz External Clock Drive External Program Memory Read Cycle External Data Memory Read Cycle AC Testing Input, Output Waveforms Oscillator Circuit Plastic Package P-LCC-44 44PLCCPlastic Package P-DIP-40 Plastic Package P-MPQF-44 GMS90X5XC Series GMS90X5XC-GC ROM Protection