Atmel AT89C51ID2 Data Sheet - Keil

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Automatic Address Recognition 54 AT89C51ID2 Figure 23. UART Timings in Modes 2 and 3 RI SMOD0=0 RI SMOD0=1 FE SMOD0=1 RXD D0 D1 D2 D3 D4 D5 D6 D7 D8 Start bit The automatic address recognition feature is enabled when the multiprocessor communication feature is enabled (SM2 bit in SCON register is set). Implemented in hardware, automatic address recognition enhances the multiprocessor communication feature by allowing the serial port to examine the address of each incoming command frame. Only when the serial port recognizes its own address, the receiver sets RI bit in SCON register to generate an interrupt. This ensures that the CPU is not interrupted by command frames addressed to other devices. If desired, the user may enable the automatic address recognition feature in mode 1.In this configuration, the stop bit takes the place of the ninth data bit. Bit RI is set only when the received command frame address matches the device’s address and is terminated by a valid stop bit. To support automatic address recognition, a device is identified by a given address and a broadcast address. Note: The multiprocessor communication and automatic address recognition features cannot be enabled in mode 0 (i. e. setting SM2 bit in SCON register in mode 0 has no effect). Given Address Each device has an individual address that is specified in SADDR register; the SADEN register is a mask byte that contains don’t-care bits (defined by zeros) to form the device’s given address. The don’t-care bits provide the flexibility to address one or more slaves at a time. The following example illustrates how a given address is formed. To address a device by its individual address, the SADEN mask byte must be 1111 1111b. For example: SADDR0101 0110b SADEN1111 1100b Given0101 01XXb The following is an example of how to use given addresses to address different slaves: Slave A:SADDR1111 0001b SADEN1111 1010b Given1111 0X0Xb Slave B:SADDR1111 0011b SADEN1111 1001b Given1111 0XX1b Slave C:SADDR1111 0010b SADEN1111 1101b Given1111 00X1b Data byte Ninth bit Stop bit 4289A–8051–09/03
4289A–8051–09/03 AT89C51ID2 The SADEN byte is selected so that each slave may be addressed separately. For slave A, bit 0 (the LSB) is a don’t-care bit; for slaves B and C, bit 0 is a 1.To communicate with slave A only, the master must send an address where bit 0 is clear (e. g. 1111 0000b). For slave A, bit 1 is a 1; for slaves B and C, bit 1 is a don’t care bit. To communicate with slaves B and C, but not slave A, the master must send an address with bits 0 and 1 both set (e. g. 1111 0011b). To communicate with slaves A, B and C, the master must send an address with bit 0 set, bit 1 clear, and bit 2 clear (e. g. 1111 0001b). Broadcast Address A broadcast address is formed from the logical OR of the SADDR and SADEN registers with zeros defined as don’t-care bits, e. g. : SADDR0101 0110b SADEN1111 1100b Broadcast =SADDR OR SADEN1111 111Xb The use of don’t-care bits provides flexibility in defining the broadcast address, however in most applications, a broadcast address is FFh. The following is an example of using broadcast addresses: Slave A:SADDR1111 0001b SADEN1111 1010b Broadcast1111 1X11b, Slave B:SADDR1111 0011b SADEN1111 1001b Broadcast1111 1X11B, Slave C:SADDR=1111 0011b SADEN1111 1101b Broadcast1111 1111b For slaves A and B, bit 2 is a don’t care bit; for slave C, bit 2 is set. To communicate with all of the slaves, the master must send an address FFh. To communicate with slaves A and B, but not slave C, the master can send and address FBh. Reset Addresses On reset, the SADDR and SADEN registers are initialized to 00h, i. e. the given and broadcast addresses are XXXX XXXXb (all don’t-care bits). This ensures that the serial port will reply to any address, and so, that it is backwards compatible with the 80C51 microcontrollers that do not support automatic address recognition. 55
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Features 80C52 Compatible - 8051 In
Page 3 and 4: Block Diagram Figure 1. Block Diagr
Page 5 and 6: Table 2. C51 Core SFRs 4289A-8051-0
Page 7 and 8: Table 8. PCA SFRs 4289A-8051-09/03
Page 9 and 10: Table 13. SFR Mapping F8h F0h E8h E
Page 11 and 12: 11 AT89C51ID2 4289A-8051-09/03 50 4
Page 13 and 14: Table 14. Pin Description (Continue
Page 15 and 16: Oscillators 4289A-8051-09/03 AT89C5
Page 17 and 18: 4289A-8051-09/03 Table 18. PCON Reg
Page 19 and 20: 4289A-8051-09/03 AT89C51ID2 It is a
Page 21 and 22: 4289A-8051-09/03 - FCLK CPU and FCL
Page 23 and 24: Figure 5. Mode Switching Waveforms
Page 25 and 26: 4289A-8051-09/03 Table 21. CKCON1 R
Page 27 and 28: 4289A-8051-09/03 Table 22. AUXR1 re
Page 29 and 30: Expanded RAM (XRAM) Figure 7. Inter
Page 31 and 32: Registers Table 23. AUXR Register A
Page 33 and 34: Reset Output 4289A-8051-09/03 AT89C
Page 35 and 36: Figure 12. Power Fail Detect Vcc 42
Page 37 and 38: Programmable Clock- Output 4289A-80
Page 39 and 40: Registers Table 24. T2CON Register
Page 41 and 42: Programmable Counter Array PCA 4289
Page 43 and 44: 4289A-8051-09/03 Table 26. CMOD Reg
Page 45 and 46: Figure 16. PCA Interrupt System 428
Page 47 and 48: 4289A-8051-09/03 Table 29. PCA Modu
Page 49 and 50: 4289A-8051-09/03 AT89C51ID2 PCA Cap
Page 51 and 52: Figure 19. PCA High Speed Output Mo
Page 53: 4289A-8051-09/03 AT89C51ID2 Serial
Page 57 and 58: Internal Baud Rate Generator (BRG)
Page 59 and 60: UART Registers Table 40. SADEN Regi
Page 61 and 62: 4289A-8051-09/03 Table 44. T2CON Re
Page 63 and 64: 4289A-8051-09/03 Table 46. BDRCON R
Page 65 and 66: 4289A-8051-09/03 AT89C51ID2 Registe
Page 67 and 68: 4289A-8051-09/03 Table 49. IPL0 Reg
Page 69 and 70: 4289A-8051-09/03 Table 51. IEN1 Reg
Page 71 and 72: 4289A-8051-09/03 Table 54. IPH1 Reg
Page 73 and 74: Power Management 4289A-8051-09/03 A
Page 75 and 76: 4289A-8051-09/03 AT89C51ID2 pins, t
Page 77 and 78: AT89C51ID2 Keyboard Interface The A
Page 79 and 80: 4289A-8051-09/03 Table 59. KBE Regi
Page 81 and 82: 4289A-8051-09/03 AT89C51ID2 2-wire
Page 83 and 84: 4289A-8051-09/03 AT89C51ID2 Descrip
Page 85 and 86: 4289A-8051-09/03 AT89C51ID2 When th
Page 87 and 88: Figure 33. Format and State in the
Page 93 and 94: Table 67. Status in Slave Receiver
Page 95 and 96: Table 68. Status in Slave Transmitt
Page 97 and 98: 4289A-8051-09/03 Bit Number 1 SD1 A
Page 99 and 100: Serial Port Interface (SPI) 4289A-8
Page 101 and 102: Functional Description Figure 38 sh
Page 103 and 104: Figure 40. Data Transmission Format
Page 105 and 106:
4289A-8051-09/03 Figure 43. SPI Int
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Serial Peripheral DATa register (SP
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WDT During Power Down and Idle 4289
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4289A-8051-09/03 AT89C51ID2 Power-o
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4289A-8051-09/03 Figure 44. Recomme
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Registers Table 85. EECON Register
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4289A-8051-09/03 AT89C51ID2 Flash M
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4289A-8051-09/03 Table 88. Program
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4289A-8051-09/03 Table 92. Program
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Functional Description Figure 48. B
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Boot Process Figure 49. Bootloader
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Functional Description 4289A-8051-0
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Flow Description 4289A-8051-09/03 A
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Write / Program Commands This flow
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Display Data Description Figure 55.
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Example 4289A-8051-09/03 Read funct
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4289A-8051-09/03 Table 95. ISP Comm
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Table 96. API Call Summary (Continu
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T A = -40°C to +85°C; V SS = 0V;
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External Program Memory Characteris
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External Program Memory Read Cycle
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External Data Memory Write Cycle 42
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AC Testing Input/Output Waveforms F
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Ordering Information 4289A-8051-09/
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VQFP44 4289A-8051-09/03 AT89C51ID2
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PLCC68 4289A-8051-09/03 AT89C51ID2
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4289A-8051-09/03 AT89C51ID2 Pulse W
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Atmel Corporation Atmel Operations
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Atmel AT89C51ID2 Data Sheet - Keil

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