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Preliminary

DS41115D-page 7

HCS101

6.0

PROGRAMMING THE HCS101

When using the HCS101 in a system, the user will have

to program some parameters into the device, including

the serial number and the counter, before it can be

used. The programming cycle allows the user to input

a 192-bit serial data stream which is then stored inter-

nally in EEPROM. Programming will be initiated by

forcing the DATA line high after the S2 line has been

held high for the appropriate length of time. Refer to

Table 6-1 and Figure 6-1.

After the Program mode is entered, a delay must be

provided to the device for the automatic bulk write cycle

to complete. This will write all locations in the EEPROM

to all zeros. The device can then be programmed by

clocking in 16 bits at a time, using S2 as the clock line

and DATA as the data in line. After each 16-bit word is

loaded, a programming delay is required for the internal

program cycle to complete. This delay can take up to

Twc.

The HCS101 will signal that the write is complete by

low on DATA. The ACK pulses will continue until S2 is

dropped. These times can be used to calculate the

oscillator calibration value. The first pulse’s width

should NOT be used for calibration.

At the end of the programming cycle, the device can be

verified as shown in Figure 6-2 by reading back the

EEPROM. Reading is done by clocking the S2 line and

reading the data bits on the DATA pin. A verify opera-

tion can only be done once, immediately following

the program cycle.

FIGURE 6-1:

PROGRAMMING WAVEFORMS

FIGURE 6-2:

VERIFY WAVEFORMS

Note:

To ensure that the device does not acci-

dentally enter Programming mode, DATA

should never be pulled high by the circuit

connected to it. Special care should be

taken when driving PNP RF transistors.

DATA

Enter Program

Mode

(Data)

(Clock)

Note: S0 and S1 button inputs to be held to ground during the entire programming sequence.

Bit 0

Bit 1

Bit 2

Bit 3

Bit 14 Bit 15

Bit 16 Bit 17

Repeat 12 times for each word

S2

Data for Word 1

Initiate Data Polling Here

Write Cycle

Complete Here

Calibration Pulses

DATA

(Clock)

(Data)

Note: If a Verify operation is to be done, then it must immediately follow the Program cycle.

End of

Programming Cycle

Begin Verify Cycle Here

Bit 1 Bit 2 Bit 3

Bit 15

Bit 14

Bit 16 Bit 17

Bit190 Bit191

Data in Word 0

S2

Bit 0

Bit191

Bit190