hcs361 Microchip Technology Inc., hcs361 Datasheet - Page 16

• Manufacturer Part Number: hcs361
• Description: Keeloq Code Hopping Encoder
• Manufacturer: Microchip Technology Inc.

HCS361
6.0
When using the HCS361 in a system, the user will have
to program some parameters into the device including
the serial number and the secret key before it can be
used. The programming cycle allows the user to input
all 192 bits in a serial data stream, which are then
stored internally in EEPROM. Programming will be
initiated by forcing the PWM line high, after the S3 line
has been held high for the appropriate length of time.
S0 should be held low during the entire program cycle.
The S1 line on the HCS361 part needs to be set or
cleared depending on the LS bit of the memory map
(Key 0) before the key is clocked in to the HCS361. S1
must remain at this level for the duration of the pro-
gramming cycle. The device can then be programmed
FIGURE 6-1:
FIGURE 6-2:
DS40146E-page 16
(Clock)
S2/S3
DATA
(Data)
End of Programming Cycle
S1
(Data)
(Clock)
DATA
S2/S3
The V
Note 1: Unused button inputs to be held to ground during the entire programming sequence.
S1
PROGRAMMING THE HCS361
Enter Program
DD
2: The V
Note: A Verify sequence is performed only once immediately after the Program cycle.
Bit190
pin must be taken to ground after a program/verify cycle.
T
Mode
2
T
Bit191
1
DD
T
Programming Waveforms
Verify Waveforms
Bit 0 of Word0
WC
Bit 0
T
pin must be taken to ground after a Program/Verify cycle.
CLKL
Ack
Bit 1
T
Bit 2
DS
Beginning of Verify Cycle
T
Bit 3
DH
Data for Word 0 (KEY_0)
Bit 0
Repeat for each word
Bit 14 Bit 15
T
Bit 1 Bit 2
CLKH
T
DV
Data from Word0
Bit 0
Bit 3
Bit 1 Bit 2
by clocking in 16 bits at a time, followed by the word’s
complement using S3 or S2 as the clock line and PWM
as the data in line. After each 16-bit word is loaded, a
programming delay is required for the internal program
cycle to complete. An Acknowledge bit can be read
back after the programming delay (T
word and its complement have been downloaded, an
automatic bulk write is performed. This delay can take
up to Twc. At the end of the programming cycle, the
device can be verified (Figure 6-1) by reading back the
EEPROM. Reading is done by clocking the S3 line and
reading the data bits on PWM. For security reasons, it
is not possible to execute a Verify function without first
programming the EEPROM. A Verify operation can
only be done once, immediately following the Pro-
gram cycle.
Bit 14
Bit 3
Bit 15
Bit 14 Bit 15
Bit 16 Bit 17
T
WC
2002 Microchip Technology Inc.
Bit 16 Bit 17
Acknowledge Pulse
Data for Word 1
WC
Bit190 Bit191
). After the first