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ADE7169 数据表(PDF) 112 Page - Analog Devices |
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ADE7169 数据表(HTML) 112 Page - Analog Devices |
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112 / 144 page ![]() ADE7566/ADE7569/ADE7166/ADE7169 Rev. A | Page 112 of 144 Mode 2 (8-Bit Timer/Counter with Autoreload) TIMER 2 Timer/Counter 2 Data Registers Mode 2 configures the timer register as an 8-bit counter (TL0) with automatic reload as shown in Figure 97. Overflow from TL0 not only sets TF0 but also reloads TL0 with the contents of TH0, which is preset by software. The reload leaves TH0 unchanged. Timer/Counter 2 also has two pairs of 8-bit data registers associated with it: Timer 2 High Byte SFR (TH2, 0xCD), Timer 2 Low Byte SFR (TL2, 0xCC), Timer 2 Reload/Capture High Byte SFR (RACP2H, 0xCB), and Timer 2 Reload/Capture Low Byte SFR (RACP2L, 0xCA). These are used as both timer data registers and as timer capture/reload registers (see CONTROL TF0 TL0 (8 BITS) INTERRUPT RELOAD TH0 (8 BITS) TR0 P0.6/T0 GATE INT0 C/T = 0 C/T = 1 fCORE Table 110 to Table 113). Timer/Counter 2 Operating Modes The following sections describe the operating modes for Timer/Counter 2. The operating modes are selected by bits in the Timer/Counter 2 Control SFR (T2CON, 0xC8), as shown in Table 105 and Table 114. Figure 97. Timer/Counter 0, Mode 2 Table 114. T2CON Operating Modes Mode 3 (Two 8-Bit Timer/Counters) RCLK (or) TCLK CAP2 TR2 Mode 0 0 1 16-bit autoreload Mode 3 has different effects on Timer 0 and Timer 1. Timer 1 in Mode 3 simply holds its count. The effect is the same as setting TR1 = 0. Timer 0 in Mode 3 establishes TL0 and TH0 as two separate counters. This configuration is shown in 0 1 1 16-bit capture 1 X 1 Baud rate X X 0 Off Figure 98. TL0 uses the Timer 0 control bits, C/T, Gate0 (see Table 103), TR0, TF0 (see 16-Bit Autoreload Mode INT0 Table 104), and . TH0 is locked into a timer function (counting machine cycles) and takes over the use of TR1 and TF1 from Timer 1. Therefore, TH0 controls the Timer 1 interrupt. Mode 3 is provided for applications requiring an extra 8-bit timer or counter. Autoreload mode has two options that are selected by Bit EXEN2 in Timer/Counter 2 Control SFR (T2CON, 0xC8). If EXEN2 = 0 when Timer 2 rolls over, it not only sets TF2 but also causes the Timer 2 registers to be reloaded with the 16-bit value in both the Timer 2 Reload/Capture High Byte SFR (RACP2H, 0xCB) and Timer 2 Reload/Capture Low Byte SFR (RACP2L, 0xCA) registers, which are preset by software. If EXEN2 = 1, Timer 2 performs the same events as when EXEN2 = 0 but adds a 1-to-0 transition at external input T2EX, which triggers the 16-bit reload and sets EXF2. Autoreload mode is shown in When Timer 0 is in Mode 3, Timer 1 can be turned on and off by switching it out of and into its own Mode 3, or it can be used by the serial interface as a baud rate generator. In fact, Timer1 can be used in any application not requiring an interrupt from Timer 1 itself. Figure 99. CONTROL CORE CLK/12 TF0 TL0 (8 BITS) INTERRUPT P0.6/T0 GATE TR0 TF1 TH0 (8 BITS) INTERRUPT fCORE/12 TR1 0 INT C/T = 0 C/T = 1 fCORE 16-Bit Capture Mode Capture mode has two options that are selected by Bit EXEN2 in Timer/Counter 2 Control SFR (T2CON, 0xC8). If EXEN2 = 0, Timer 2 is a 16-bit timer or counter that, upon overflowing, sets Bit TF2, the Timer 2 overflow bit, which can be used to generate an interrupt. If EXEN2 = 1, Timer 2 performs the same events as when EXEN2 = 0 but adds a l-to-0 transition on external input T2E, which causes the current value in the Timer 2 registers, TL2 and TH2, to be captured into the RCAP2L and RCAP2H registers, respectively. In addition, the transition at T2EX causes Bit EXF2 in T2CON to be set, and EXF2, like TF2, can generate an interrupt. Capture mode is shown in Figure 100. The baud rate generator mode is selected by RCLK = 1 and/or TCLK = 1. In either case, if Timer 2 is used to generate the baud rate, the TF2 interrupt flag does not occur. Therefore, Timer 2 interrupts do not occur and do not have to be disabled. In this mode, the EXF2 flag can, however, still cause interrupts that can be used as a third external interrupt. Baud rate generation is described as part of the UART serial port operation in the Figure 98. Timer/Counter 0, Mode 3 UART Serial Interface section. |
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