HCS362-I Datasheet, PDF (17/38 Pages) Microchip Technology – KEELOQ Code Hopping Encoder

HCS362
4.5.5 GUARD
The Guard time between code words can be set to 0
ms, 6.4 ms, 25.6 ms and 76.8 ms. If during a series of
code words, the output changes from Hopping Code to
Seed the Guard time will increase by 3 x TE.
4.5.6 TIMOUT[0..1]
The transmission time-out can be set to 0.8 s, 3.2 s,
25.6 s or no time-out. After the time-out period, the
encoder will stop transmission and enter a low power
Shutdown mode.
TABLE 4-3: CONFIG_1
Bit
Address
0
1
2
...
8
9
10
11
12
13
Field
DISC_0
DISC_1
DISC_2
...
DISC_8
DISC_9
OVR_0
OVR_1
XSER
SEEDC
Description
Discrimination bits
DISC[9:0]
Values
Overflow
OVR[1:0]
Extended Serial Number
Seed Control
0 - Disable
1 - Enable
0 = Seed transmission on:
S[3210] = 0001 (delay 1.6 s)
S[3210] = 0101 (immediate)
1 = Seed transmission on:
S[3210] = 0011 (delay 3.2 s)
S[3210] = 1001 (immediate)
14
SEED_0
Seed options
15
SEED_1
4.5.7 DISC[0..9]
The discrimination bits are used to validate the
decrypted code word. The discrimination value is typi-
cally programmed with the 10 Least Significant bits of
the serial number or a fixed value.
4.5.8 OVR[0..1]
The overflow bits are used to extend the possible code
combinations to 192K. If the overflow bits are not going
to be used they can be programmed to zero.
4.5.9 XSER
If XSER is enabled a 32-bit serial number is transmit-
ted. If XSER is disabled a 28-bit serial number and a 4-
bit function code are transmitted.
00 - No Seed
01 - Limited Seed (Permanent and Delayed)
10 - Permanent and Delayed Seed
11 - Permanent Seed only
4.5.10 SEED[0..1]
The seed value which is transmitted on key combina-
tions (0011) and (1001) can be disabled, enabled or
enabled for a limited number of transmissions deter-
mined by the initial counter value.
In limited Seed mode, the device will output the seed if
the sync counter (Section 4.2) is from 00hex to 7Fhex.
For a counter higher than 7F, a normal hopping code
will be output.
Note:
Whenever a SEED code word is output,
the 4 function bits (Figure 7-4) will be set to
all ones [1,1,1,1].
4.5.11 SEEDC
SEEDC selects between seed transmission on 0001
and 0101 (SEEDC = 0) and 0011 and 1001 (SEEDC
= 1). The delay before seed transmission is 1.6 s for
(SEEDC = 0) and 3.2 s for (SEEDC = 1).
© 2002 Microchip Technology Inc.
Preliminary
DS40189D-page 17