HCS515_11 Datasheet, PDF (11/38 Pages) Microchip Technology – KEELOQ® Code Hopping Decoder stand-alone decoder

HCS515
4.2.5
READ BYTE/S FROM USER
EEPROM
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
truncated to 7 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). Sequen-
tial 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). 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.
4.2.6 WRITE BYTE/S TO USER EEPROM
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 (LSb) 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 keeping it high until the clock line
goes low.
FIGURE 4-4: READ BYTES FROM USER EEPROM
TRD
TRD
CLK
μC DATA
LSB
MSB LSB
MSB LSB
MSB
Decoder DATA
START Command
A
B
Command Byte
C
Address Byte
D
Dummy Byte
LSB
MSB
Data Byte
E
F
FIGURE 4-5: WRITE BYTES TO USER EEPROM
TWR
CLK
μC DATA
LSB
MSB LSB
MSB LSB
MSB
Decoder DATA
START Command
Command Byte
Address Byte
Data Byte
A
B
C
D
E
TACK
TRESP
TACK2
Acknowledge
F
© 2011 Microchip Technology Inc.
DS40183E-page 11