MCP413X/415X/423X/425X
7.6.1
SINGLE READ
7.6
Read Data
Normal and High Voltage
The read operation requires that the CS pin be in the
active state (VILor VIHH). Typically, the CS pin will be in
the inactive state (VIH) and is driven to the active state
(VILor VIHH). The 16-bit Read Command (Command
Byte and Data Byte) is then clocked in on the SCK and
SDI pins. The SDO pin starts driving data on the 7th bit
(CMDERR bit) and the addressed data comes out on
the 8th through 16th clocks. Figure 6-3 through
Figure 6-6 show possible waveforms for a single read.
Note:
The High Voltage Read Data command is
supported for compatability with system
that also support MCP414X/416X/424X/
426X devices.
The Read command is a 16-bit command. The format
of the command is shown in Figure 7-4.
The first 6-bits of the Read command determine the
address and the command. The 7th clock will output
the CMDERR bit on the SDO pin. The remaining
9-clocks the device will transmit the 9 data bits (D8:D0)
of the specified address (AD3:AD0).
Figure 6-5 and Figure 6-6 show the single read
waveforms when the SDI and SDO signals are
multiplexed on the same pin. For additional information
on the multiplexing of these signals, refer to
Section 6.1.3 “SDI/SDO”.
Figure 7-4 shows the SDI and SDO information for a
Read command.
COMMAND BYTE
DATA BYTE
A
D
3
A
D
2
A
D
1
A
D
0
1
1
X
X
X
X
X
X
X
X
X
X
SDI
1
1
1
1
1
1
1
1
1
0
D
8
D
7
D
6
D
5
D
4
D
3
D
2
D
1
D Valid Address/Command combination
0
SDO
1
1
1
1
0
0
0
0
0
0
0
0
0
Attempted Memory Read of Reserved
Memory location.
READ DATA
Read Command - SDI and SDO States.
FIGURE 7-4:
© 2008 Microchip Technology Inc.
DS22060B-page 53
MICROCHIP [ MICROCHIP ]
