HCS500-IP Microchip Technology, HCS500-IP Datasheet - Page 10

• Manufacturer Part Number: HCS500-IP
• Description: KEELOQ CODE HOPPING ENCODER
• Manufacturer: Microchip Technology

HCS500
4.2.5
The read command (Figure 4-4) is used to read bytes
from the user EEPROM. The offset in the user
EEPROM is specified by the address byte which is trun-
cated to seven bits (C to D). After the address, a
dummy byte must be clocked in (D to E). The EEPROM
data byte is clocked out on the next rising edge of the
clock line with the least significant bit first (E to F).
Sequential reads are possible by repeating sequence E
to F within 1 ms after the falling edge of the previous
byte’s Most Significant Bit (MSB) bit. During the
sequential read, the address value will wrap after 128
bytes. The decoder will terminate the read command if
no clock pulses are received for a period longer than
1.2 ms.
FIGURE 4-4:
FIGURE 4-5:
DS40153B-page 10
Decoder DATA
Decoder DATA
C DATA
C DATA
CLK
READ BYTE/S FROM USER EEPROM
CLK
A
A
Start Command
Start Command
READ BYTES FROM USER EEPROM
WRITE BYTES TO USER EEPROM
B
B
LSB
LSB
Command Byte
Command Byte
MSB
MSB
C
C
LSB
LSB
Preliminary
Address Byte
Address Byte
MSB
4.2.6
The write command (Figure 4-5) is used to write a loca-
tion in the user EEPROM. The address byte is trun-
cated to seven bits (C to D). The data is clocked in least
significant bit first. The clock line must be asserted to
initiate the write. Sequential writes of bytes are possible
by clocking in the byte and then asserting the clock line
(D – F). The decoder will terminate the write command
if no clock pulses are received for a period longer than
1.2 ms After a successful write sequence the decoder
will acknowledge by taking the data line high and keep-
ing it high until the clock line goes low.
MSB
D
D
LSB
LSB
WRITE BYTE/S TO USER EEPROM
Data Byte
Dummy Byte
MSB
MSB
T
T
WR
RD
1997 Microchip Technology Inc.
E
E
LSB
Acknowledge
T
Data Byte
ACK
T
RESP
T
ACK
MSB
2
T
RD
F
F