qf4a512 ETC-unknow, qf4a512 Datasheet - Page 30

• Manufacturer Part Number: qf4a512
• Description: 4-channel Programmable Signal Converter Psc
• Manufacturer: ETC-unknow

In Configure mode 14-bit address words are used. In Run mode 8-bit addressing is used. These differences are shown graphically in
the following diagram. Consequently the host controller must use the appropriate timing depending on which mode of operation is
active. (At power up the mode of operation is determined by the value of the auto_start bit (register STARTUP_1).
If it is unknown which mode is active there are several ways to determine this. If in Run mode there should be a continuous stream of
conversions occurring which should be reflected by changes in level of the DRDY pin, furthermore if SCLK is active and CSN is held
low there should be transitions occurring on the SDO pin. These pins can me monitored for activity within a pre-determined timeout
interval. These methods are summarized below.
Rev C5, Jan 07
Configure Mode Writes
Run Mode Writes :
1.
2.
Multiple Channels
Run Mode Writes :
Single Channel
If the QF4A512 is in Run mode, DRDY will be driven high when the fastest sample is available. If in Configure mode, DRDY is
an input (internal pull-down in the chip). So, by monitoring DRDY you can determine the mode of operation.
Holding SDI low (to prevent inadvertently writing any bad info to the chip), toggle SCLK and look for data on SDO. If in
Configure mode, SDO will be low the whole time. If in Run mode, SDO will eventually toggle.
DRDY (o/p)
DRDY (o/p)
SCLK (i/p)
SDO (o/p)
SCLK (i/p)
SDO (o/p)
CSN (i/p)
CSN (i/p)
SDI (i/p)
SDI (i/p)
DRDY (i/p)
SCLK (i/p)
SDO (o/p)
CSN (i/p)
SDI (i/p)
Bit #
Bit #
Bit #
Figure 13. Comparison of Configure and Run Mode Timing
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
15 14 13 12 11 10 9
23
0
p
22 21 20 19 18 17 16 15 14 13 12 11 10 9
i1 i0 n
8-bit address
8-bit address
0
PRELIMINARY
16-bit ch N filter data
14-bit address
0
30
0
8
0
7
6
8-bit write data
8-bit write data
8-bit write data
5
4
3
2
16-bit ch N filter data
1
8
0
8
7
7
6
6
8-bit write data
5
5
4
4
15 14 13 12 11 10 9
3
3
2
2
www.quickfiltertech.com
16-bit ch N filter data
1
1
8-bit address
0
0
QF4A512
8