ISL78610 Datasheet, PDF (56/98 Pages) Intersil Corporation – Multi-Cell Li-Ion Battery Manager

ISL78610
SCLK
DIN
SPI
DOUT
CS
DATA READY
MASTER Tx
MASTER Rx
DAISY
CHAIN
DEVICE 4 Tx
DEVICE 4 Rx
DEVICE 10 Tx
DEVICE 10 Rx
AAA
BBB B
PACKET A
10 EXTRA
CLOCKS
4 DAISY CLOCK PULSES
PACKET A
6 EXTRA
CLOCKS
PACKET B
PACKET B
NO EXTRA
CLOCKS
4 EXTRA
CLOCKS
ACK
ACK
10 EXTRA
CLOCKS
5 EXTRA
CLOCKS
PACKET A
NO EXTRA CLOCKS
10 DAISY CLOCK PULSES
• Host microcontroller sends “Read device 4, cell 7” = Packet A
• Master begins relaying Packet A following receipt of the first byte of
A. Master adds 10 extra clock cycles to allow all stack devices to relay
the message.
• Device 4 receives and decodes “Read device 4, cell 7” and waits for a
response from top stack device.
• Top of stack (device 10) receives and decodes Packet A.
• Device 10 responds “ACK”. Device 10 adds 10 clock cycles to allow
all stack devices to relay the message.
• Device 4 receives and decodes ACK.
• Device 4 transmits the cell 7 data = Packet B. Device 4 subtracts one
clock cycle to synchronize timing for lower stack devices to relay the
message.
• Master asserts DATA READY after receiving the first byte of Packet B.
• Host responds by asserting CS and clocking out 8 bits of data from
DOUT. CS is taken high following the 8th bit. The master responds by
taking DATA READY high and tri-stating DOUT. Master asserts
DATA READY after receiving the next byte and so on.
FIGURE 65. DAISY CHAIN READ EXAMPLE “READ DEVICE 4, CELL 7”. STACK OF 10 DEVICES
TABLE 25. ISL78610 DATA INTERPRETATION RULES FOR DAISY CHAIN INSTALLATIONS
FIRST 4 BITS IN SEQUENCE
5^TH BIT
(R/W)
PAGE DATA ADDRESS
INTERPRETATION
Stack address [3:0] (nonzero)
0
011
001000 Measure command. Data address is followed by 6-bit element address.
0000
0
011
001001 Identify command. Data address is followed by device count data.
Stack address [3:0] (nonzero)
0
Any
All other Device Read command. Data address is followed by 6 zeros.
Stack address [3:0] (nonzero)
1
Any
Any
Device Write command.
Communication Sequences
All daisy chain device responses are 4-byte sequences, except for
the responses to the Read All command. All responses start with
the device stack address. All responses use a 4-bit CRC. The
response to the “Read All Commands” is to send a normal 4-byte
data response for the first data segment and continue sending the
remaining data segments in 3-byte sections composed of data
address, data and CRC. This creates an anomaly with the normal
CRC usage in that the first 4 bytes have a 4-bit CRC at the end
(operating on 3.5 bytes of data) while the remaining bytes have a
CRC which only operates on 2.5 bytes. The host microcontroller,
having requested the data, must be prepared for this.
Daisy chain devices require device stack address information to
be added to the basic command set. Daisy chain writes are
4-byte sequences. Daisy chain reads are 3 bytes. Action
commands, such as scan and communications administration
commands are treated as reads. Daisy chain communications
employ a 4-bit CRC (Cyclic Redundancy Check) using a
polynomial of the form 1 + X + X⁴. The first four bits of each daisy
chain transmission contain the stack address, which can be any
number from 0001 to 1110. All devices respond to the Address
All (1111) and Identify (0000) stack addresses. The fifth bit is set
to ‘1’ for write and ‘0’ for read. The rules for daisy chain
installations are shown in Table 25.
CRC Calculation
Daisy chain communications employ a 4-bit CRC using a
polynomial of the form 1 + X + X⁴. The polynomial is
implemented as a 4-stage internal XOR standard linear feedback
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FN8830.1
June 16, 2016