CS5521 CS5523
18
DS317PP2
the way to access the resulting data is determined
by the MC (multiple conversion), the LP (loop),
and the RC (read convert) bits in the configuration
register. MC’s, LP’s, and RC’s functional descrip-
tions follow. The other bits in the configuration
register are detailed in Table 4.
MC = 0 LP = 0 RC = X
Based on the information provided in the channel-
setup registers (CSRs), a single conversion is per-
formed on the physical channel referenced by the
logical channel. The command byte contains the
pointer address of the logical channel to be used
during the conversion embedded in it. The serial
port enters data mode as soon as the 8-bit command
byte to start a conversion is issued. The port re-
mains in data mode during conversion. Upon the
completion of the conversion, SDO falls to logic 0.
Thirty-two SCLKs are needed to acquire the con-
version. The first 8 SCLKs are used to clear the
SDO flag. The last 24 are needed to read the con-
version result. After reading the data, the serial port
returns to the command mode, where it waits for a
new command to be issued.
MC = 0 LP = 1 RC = 0
Based on information contained in the CSRs, a sin-
gle conversion is repeatedly performed on the
physical channel referenced by the logical channel.
The command byte contains the pointer address of
the logical channel to be used during conversion.
Once a conversion is complete, SDO falls to indi-
cate that a conversion is ready. Thirty-two SCLKs
are needed to acquire the conversion (which must
be acquired within a certain window, refer to Fig-
ure 6). The first 8 SCLKs are used to clear the SDO
flag. The next 24 are needed to read the conversion
result. If ‘00000000’ is provided to SDI during the
first 8 SCLKs when the SDO flag is cleared, the
converter remains in this conversion mode and
continues to convert the selected channel. While in
this mode, the user may choose to acquire only the
conversions required for his application as SDO
rises and falls to indicate the availability of a new
conversion. To exit this conversion mode the user
must provide ‘11111111’ to the SDI pin during the
first 8 SCLKs. If the user decides to exit, 24 SCLKs
are required to clock out the last conversion before
the converter will return to the command mode.
MC = 0 LP = 1 RC = 1
Based on information provided in the CSRs, a sin-
gle conversion is performed repeatedly on the
physical channel referenced by the logical channel.
The command byte contains the pointer address of
the logical channel to be used during the conver-
sion embedded in it. After a conversion cycle is
complete, SDO falls and the serial port is placed in
the data mode where it will remain until the conver-
sion data is read. If the user doesn’t read the con-
version word the converter stops performing new
conversions and SDO will remain low until the
conversion data is acquired. To acquire the conver-
sion data thirty-two SCLKs are needed. The first 8
SCLKs are used to clear the SDO flag. The next 24
are needed to read the conversion result. If
‘00000000’ is provided to SDI during the first 8
SCLKs to clear the SDO flag, a new conversion cy-
cle will be started after the conversion data is read.
To exit this conversion mode and return to the com-
mand mode, the user must provide ‘11111111’ to
the SDI during the first 8 SCLKs. A final 24
SCLKs are required to clock out the last conversion
data.
MC = 1 LP = 0 RC = X
Based on information provided in the CSRs, multi-
ple conversions are performed once on the physical
channels referenced by the logical channels of the
CSRs. The first two conversions are based on the
information in the channel-setup register (CSR) #1
(logical channels one and two); the third and fourth
conversions are based on information in the CSR
#2 (logical channels three and four); and so on up
to 8 conversions when the CS5523 is used. The
depth (DP2-DP0) information bits in the configura-
