DS2409 Dallas Semiconducotr, DS2409 Datasheet
DS2409
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DS2409 Summary of contents
Page 1
... PIN ASSIGNMENT 6-PIN TSOC PACKAGE TOP VIEW 3.7 X 4.0 X 1.5 mm SIDE VIEW PIN DESCRIPTION Pin 1 GND Pin 2 1-Wire in Pin 3 Main 1-Wire out Pin 4 Auxiliary 1-Wire out Pin 5 Control Output Pin ORDERING INFORMATION DS2409P 6-pin TSOC package DS2409 102199 ...
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... The DS2409 uses the standard Dallas Semiconductor 1-Wire protocol for data transfers (Figure 2), with all data being read and written least significant bit first. Communication to and from the DS2409 requires a single bi-directional line that is typically a port pin of a microcontroller. The 1-Wire bus master (microcontroller) must first issue one of five ROM function commands: 1) Read ROM, 2) Match ROM, 3) Search ROM, 4) Skip ROM Conditional Search ROM ...
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... LASERED ROM Each DS2409 contains a unique ROM code that is 64 bits long. The first eight bits are a 1-Wire family code. The next 48 bits are a unique serial number. The last eight bits are a CRC of the first 56 bits. (See Figure 3.) The 1-Wire CRC of the lasered ROM is generated using the polynomial X Additional information about the Dallas Semiconductor 1-Wire Cyclic Redundancy Check is available in the Book of DS19xx iButton Standards ...
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... If a 1-Wire output is inactive and a low-going edge is encountered during this time, the DS2409 will set the event flag (EVNT) the status info byte. Each output has its own event flag. The event flags are cleared with the All Lines Off command. Bit 7 of the status info byte tells if the device is auto- control mode or manual mode ...
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... Otherwise one might inadvertently clear the event flag without having taken appropriate action. If the DS2409 is in auto- control mode, the transistor at the control output will be switched off (non-conducting). At power-on, the device will automatically perform the All Lines Off command ...
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... The first 8 time slots (reset stimulus) are translated by the DS2409 as a reset low time on the Main 1-Wire output. Now the bus master reads the reset response byte. This generates the reset high time where devices connected to the Main 1-Wire output may assert their presence pulse ...
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... FUNCTION COMMAND FLOW CHART Figure DS2409 102199 ...
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... FUNCTION COMMAND FLOW CHART Figure 5 cont’ DS2409 102199 ...
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... MUST be left in the idle state if the transaction is to resume. If this does not occur and the bus is left low for more than 120 µs, one or more of the devices on the bus may be reset. The DS2409 may perform a power-on reset cycle and deactivate both 1-Wire outputs if the 1-Wire input is low for minimum 8 ms. A low time more will always cause a power-on reset cycle ...
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... This command allows the bus master to read the DS2409s 8-bit family code, unique 48-bit serial number, and 8-bit CRC. This command can only be used if there is a single DS2409 on the bus. If more than one slave is present on the bus, a data collision will occur when all slaves try to transmit at the same time (open drain will produce a wired-AND result) ...
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... ROM FUNCTIONS FLOW CHART Figure DS2409 102199 ...
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... DS2409. During write time slots, the delay circuit determines when the DS2409 will sample the data line. For a read data time slot “0” transmitted, the delay circuit determines how long the DS2409 will hold the data line low overriding the 1 generated by the master. If the data bit is a “ ...
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... READ/WRITE TIMING DIAGRAM Figure DS2409 102199 ...
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... USAGE EXAMPLE Configuration: A bus master controls a MicroLAN consisting of a trunk with many DS2409s that create branches. Each of the DS2409s has a DS2430A connected to its auxiliary output to label its physical location in the network (see Figure 10). iButton devices are constantly arriving at or departing from the branches. Task: Identify one branch where an iButton has arrived and get the branch’ ...
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... APPLICATION EXAMPLES Figures 10 and 11 show two application examples of the DS2409 MicroLAN Coupler. A single trunk with branches is the typical topology of an access control system with the iButtons being the electronic keys required for admittance. The host computer runs a program that scans the devices on the trunk for events (conditional search) ...
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... DUAL MASTER SYSTEM Figure DS2409 102199 ...
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... LOC I 10 OLC DDQ SYMBOL MIN TYP C IN1 C INM C INA SYMBOL MIN TYP Z 10 MON Z 15 AON R 1 DS2409 = 5V ±10%) DD MAX UNITS NOTES +0 0 PUP µ +0 +0 ...
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... RSTL otherwise, it could mask or conceal interrupt pulses. The DS2409 may perform a power-on reset cycle and deactivate both 1-Wire outputs if the 1-Wire input is low for minimum 8 ms. A low time more will always cause a power-on reset cycle. ...