qf4a512 ETC-unknow, qf4a512 Datasheet - Page 29

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

PRELIMINARY
QF4A512
Figure 12. Run Mode Timing, Read and Write
Note: Once set by the chip DRDY will remain high until /CS is pulled low.
10.4 Sending Commands in Run Mode
Although Run mode exists primarily to output filtered data from the ADC it is also possible to issue commands to the QF4A512 in this
mode. Of fundamental importance is the ability to write the command to exit run mode and return to Configure mode!
In fact, it is possible to write to any register (that allows writes) within the first 8 bits of address space (Registers 00h – FFh). The format
and timing can be seen in Figures 10 and 11. In the register descriptions (Chapter 12) all registers are writeable (R/W) except those
specifically designated as Read Only or Auto Set. Obviously since the output data is dedicated to filtered conversion results from the
ADC it is not possible to read any of the control registers while in Run mode (except of course for data which is included in the header
of the MSB, for example, the new data flags).
The most likely registers to be used for dynamic adjustment during Run mode are as follows:
GLBL_SW (00h)
Actually being used as a dummy register, it is useful to set the control address to 00h when no commands are being issued to prevent
inadvertent writes to other command registers.
RUN_MODE (04h)
Writing a 0 to bit 0 will take the QF4A512 out of Run mode and back to Configure mode.
ENABLE_2 (0Bh)
The 4 lsb’s can be used to turn on/off data in the output data stream (arec_ch_en bits). This can be useful to regulate SPI bandwidth
when using multiple channels with varying sample rates.
CHn_PGA (30h, 60h, 90h, C0h)
The pga_gain bits can be used to vary the PGA gain on a per channel basis.
CAL_n_OFF (56h,57h, 86h, 87h, B6h, B7h, E6h, E7h)
Offset calibration value for channel n.
CAL_n_GAIN (58h,59h, 88h, 89h, B8h, B9h, E8h, E9h)
Gain calibration value for channel n.
Note: There are differences in the way the address and data is formatted between Run Mode and Configure mode.
Rev C5, Jan 07
29
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