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PSD813F2 数据表(PDF) 56 Page - STMicroelectronics |
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PSD813F2 数据表(HTML) 56 Page - STMicroelectronics |
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56 / 110 page ![]() PSD813F2, PSD833F2, PSD834F2, PSD853F2, PSD854F2 56/110 JTAG In-System Programming (ISP) Port C is JTAG compliant, and can be used for In- System Programming (ISP). You can multiplex JTAG operations with other functions on Port C because In-System Programming (ISP) is not per- formed in normal Operating mode. For more infor- mation on the JTAG Port, see the section entitled PROGRAMMING IN-CIRCUIT USING THE JTAG SERIAL INTERFACE, page 69. Port Configuration Registers (PCR) Each Port has a set of Port Configuration Regis- ters (PCR) used for configuration. The contents of the registers can be accessed by the MCU through normal READ/WRITE bus cycles at the addresses given in Table 7., page 18. The addresses in Ta- ble 7 are the offsets in hexadecimal from the base of the CSIOP register. The pins of a port are individually configurable and each bit in the register controls its respective pin. For example, Bit 0 in a register refers to Bit 0 of its port. The three Port Configuration Registers (PCR), shown in Table 22, are used for setting the Port configurations. The default Power-up state for each register in Table 22 is 00h. Control Register Any bit reset to '0' in the Control Register sets the corresponding port pin to MCU I/O Mode, and a '1' sets it to Address Out Mode. The default mode is MCU I/O. Only Ports A and B have an associated Control Register. Direction Register The Direction Register, in conjunction with the out- put enable (except for Port D), controls the direc- tion of data flow in the I/O Ports. Any bit set to '1' in the Direction Register causes the correspond- ing pin to be an output, and any bit set to '0' causes it to be an input. The default mode for all port pins is input. Figure 28., page 58 and Figure 29., page 59 show the Port Architecture diagrams for Ports A/B and C, respectively. The direction of data flow for Ports A, B, and C are controlled not only by the direction register, but also by the output enable product term from the PLD AND Array. If the output enable product term is not active, the Direction Register has sole control of a given pin’s direction. An example of a configuration for a Port with the three least significant bits set to output and the re- mainder set to input is shown in Table 25. Since Port D only contains three pins (shown in Figure 31., page 61), the Direction Register for Port D has only the three least significant bits active. Drive Select Register The Drive Select Register configures the pin driver as Open Drain or CMOS for some port pins, and controls the slew rate for the other port pins. An external pull-up resistor should be used for pins configured as Open Drain. A pin can be configured as Open Drain if its corre- sponding bit in the Drive Select Register is set to a ’1.’ The default pin drive is CMOS. Note that the slew rate is a measurement of the rise and fall times of an output. A higher slew rate means a faster output response and may create more electrical noise. A pin operates in a high slew rate when the corresponding bit in the Drive Reg- ister is set to ’1.’ The default rate is slow slew. Table 26., page 57 shows the Drive Register for Ports A, B, C, and D. It summarizes which pins can be configured as Open Drain outputs and which pins the slew rate can be set for. Table 22. Port Configuration Registers (PCR) Note: 1. See Table 26., page 57 for Drive Register bit definition. Table 23. Port Pin Direction Control, Output Enable P.T. Not Defined Table 24. Port Pin Direction Control, Output Enable P.T. Defined Table 25. Port Direction Assignment Example Register Name Port MCU Access Control A,B WRITE/READ Direction A,B,C,D WRITE/READ Drive Select1 A,B,C,D WRITE/READ Direction Register Bit Port Pin Mode 0 Input 1 Output Direction Register Bit Output Enable P.T. Port Pin Mode 0 0 Input 0 1 Output 1 0 Output 1 1 Output Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 0 0 0 0 0 1 1 1 |
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