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DNT24 Integration Guide - 10/19/11
The DNT24 SPI port can run at three clock rates in master mode - 125, 250 or 500 kbps. There are two
message sources available to a DNT24 SPI master, a protocol-formatted
RxData
message or a stored
command. The DNT24 master will clock a message from either source into its slave and return the bytes
clocked out as a protocol-formatted
TxData
message. The DNT24 event timer triggers sending the stored
command to the DNT24’s slave. The stored command can be up to 16 bytes in length. Figure 3.2.1
shows the required SPI master mode-signal connections, and Figure 3.2.2 shows the SPI master-mode
timing.
/ S S
S C L K
M O S I
M I S O
S P I B i t C l o c k
C o m m a n d t o S l a v e
D a t a f r o m S l a v e
D N T 2 4 S P I M a s t e r M o d e O p e r a t i o n
Figure 3.2.2
In SPI slave mode, the host can stream data into DNT24 at up to 250 kbps, provided the host suspends
clocking within 10 bytes following a low-to-high transition on /HOST_CTS. The host can clock data into
the DNT24 at up to 4 Mbps for data bursts of up to 50 bytes, provided the interval from the end of one
burst to the start of the next burst is at least 2 ms, and the host suspends clocking on a low-to-high transi-
tion on /HOST_CTS. See Figure 3.2.4
D N T 9 0
H o s t
D N T 2 4 S P I S l a v e M o d e S i g n a l i n g
/ S S
S C L K
M O S I
M I S O
/ H O S T _ C T S
D A V
/ H O S T _ R T S
Figure 3.2.3