Rainbow-electronics DS2422 Manuel d'utilisateur

1 of 25 022102FEATURES§ 4096 bits of SRAM (DS2423), 1024 bits withthe DS2422§ Four 32-bit, read-only counters (DS2423),three counters with the DS242

DS2422/DS242310 of 25MEMORY FUNCTION FLOW CHART Figure 7 cont’d

DS2422/DS242311 of 25MEMORY FUNCTION FLOW CHART Figure 7 cont’d

DS2422/DS242312 of 25MEMORY FUNCTION EXAMPLE (DS2423)Example: Write two data bytes to memory location 0026 and 0027. Read entire memory.MASTER MODE DA

DS2422/DS242313 of 25MEMORY FUNCTION EXAMPLE (DS2423)Read page 14 and counts of Input A. Rewrite page 14 with 32 bytes. Read Memory + Counter, WriteSc

DS2422/DS242314 of 25HARDWARE CONFIGURATION Figure 8Note: Depending on the 1-Wire communication speed and the bus load characteristics, the optimal pu

DS2422/DS242315 of 25INITIALIZATIONAll transactions on the 1-Wire bus begin with an initialization sequence. The initialization sequenceconsists of a

DS2422/DS242316 of 25When issued on a multidrop bus this command will set all Overdrive-supporting devices into Overdrivemode. To subsequently addres

DS2422/DS242317 of 25ROM FUNCTIONS FLOW CHART Figure 9 (First Part)

DS2422/DS242318 of 25ROM FUNCTIONS FLOW CHART Figure 9 cont’d

DS2422/DS242319 of 251-WIRE SIGNALINGThe DS242X requires strict protocols to ensure data integrity. The protocol consists of four types ofsignaling on

DS2422/DS24232 of 25triggered by inputs A and B, respectively, increment with every low-going pulse on their input. Allcounters are read-only. They ar

DS2422/DS242320 of 25READ/WRITE TIMING DIAGRAM Figure 11

DS2422/DS242321 of 25CRC GENERATIONWith the DS242X there are two different types of CRCs (Cyclic Redundancy Checks). One CRC is an 8-bit type and is s

DS2422/DS242322 of 25CRC-16 HARDWARE DESCRIPTION AND POLYNOMIAL Figure 12

DS2422/DS242323 of 25ABSOLUTE MAXIMUM RATINGS*Voltage on Any Pin Relative to Ground -0.5V to +7.0VOperating Temperature Range -40°C to +85°CStorage Te

DS2422/DS242324 of 25AC CHARACTERISTICS REGULAR SPEED(VPUP = 2.8V to 6.0V; VBAT = 2.8 to 5.5V;-40°C to +85°C)PARAMETER SYMBOL MIN TYP MAX UNITS NOTEST

DS2422/DS242325 of 25NOTES:1) All voltages are referenced to ground.2) VPUP = external pullup voltage.3) Input load is to ground.4) An additional

DS2422/DS24233 of 25is entered. After the 48th bit of the serial number has been entered, the shift register contains the CRCvalue. Shifting in the 8

DS2422/DS24234 of 25The highest valued bit of the E/S register, called AA or Authorization Accepted, acts as a flag to indicatethat the data stored in

DS2422/DS24235 of 25WRITING WITH VERIFICATIONTo write data to the DS242X, the scratchpad has to be used as intermediate storage. First the masterissue

DS2422/DS24236 of 25Read Scratchpad Command [AAH]This command is used to verify scratchpad data and target address. After issuing the Read Scratchpadc

DS2422/DS24237 of 25DS242X MEMORY MAP Figure 5ADDRESS REGISTERS Figure 6Read Memory [F0H]The read memory command may be used to read the entire memory

DS2422/DS24238 of 25important to realize that the target address registers will contain the address provided. The endingoffset/data status byte is una

DS2422/DS24239 of 25MEMORY FUNCTION FLOW CHART Figure 7