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7549 Datasheet(PDF) 47 Page - Renesas Technology Corp |
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7549 Datasheet(HTML) 47 Page - Renesas Technology Corp |
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47 / 73 page  Rev.2.00 Mar 05, 2007 Page 47 of 70 REJ03B0202-0200 7549 Group PRELIMINARY Notice: This is not a final specification. Some parametric limits are subject to change. Fig 62. Block diagram of internal clock generating circuit “00”: Low-speed mode High-speed on-chip oscillator (HSOCO) 1/4 1/2 Timing φ (Internal clock) φSOURCE “10”: High-speed mode Clock division ratio selection bits WIT instruction Low-speed on-chip oscillator (LSOCO) 1/8 “01”: Middle-speed mode “11”: Double-speed mode Peripheral function clock generation circuit (1/1 to 1/256) Clock selection bits High-speed on-chip oscillator oscillation control bit Low-speed on-chip oscillator oscillation control bit 1/16 Prescaler 12 Timer 1 Oscillation stabilization time set timer after release of the STP instruction SQ R Reset Interrupt disable flag I Interrupt request XIN/XCIN oscillation control bit Bits 0 and 1 of FSROM1: setting of the oscillation method setection bits “00”: Clock pins not used P21/XIN/XCIN Port P21 control circuit P20/XOUT/XCOUT Port P20 control circuit “10” “01” “00” It is not possible to write “1” to the low-speed on-chip oscillator oscillation control bit if low-speed on-chip oscillator stop has been disabled by bit 4 in FSROM2. Also, the low-speed on-chip oscillator does not stop even if the STP instruction is executed. XIN oscillation cannot be selected as φSOURCE if clock pins not used is selected. P21/XIN/XCIN Port P21 control circuit P20/XOUT/XCOUT “11”: External clock input Noise filter P21/XIN/XCIN P20/XOUT/XCOUT Rf “10”: 32 kHz quartz- crystal oscillation P21/XIN/XCIN P20/XOUT/XCOUT Rf “01”: Ceramic or quartz- crystal oscillation 1/1 to 1/256 Peripheral function (Note 2) (Note 2) Reset SQ R QS STP instruction STP instruction R Notes 1: The oscillation circuit is built in the P20/XOUT/XCOUT pin and the P21/XIN/XCIN pin. When the Vcc of the microcomputer is lower than the operation lower bound voltage even if these pins are used as I/O ports, the oscillation circuit is connected and undefined values may be output from these pins. 2: Although a feed-back resistor exists on-chip, an external feed-back resistor may be needed depending on conditions. |
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