Cypress S6J3200 Series, Руководство пользователя

Страница: 278 / 1355

CHAPTER 15:12-/10-/8-bit Analog to Digital Converter
S6J3200 Series Hardware Manual Document Number: 002-04852 Rev. *G 277
3.9.
DMA Transfer Function
There are four conversion done DMA triggers available. They can be configured through the
corresponding ADC12Bn_CDDS0 to 3 registers:
−
The bit field CDCHNUM specifies the logical channel number whose conversion done
interrupt flag issues a DMA request,
−
CDCHEN bit controls enabling/disabling of the DMA request.
The feature provides an efficient way to transfer A/D conversion results to memory. Selecting of the group
last logical channels through the four CDCHNUM bit fields can configure four different groups for DMA
transfers. Since the group is always made of consecutive logical channels and the corresponding
conversion data registers can be read linearly, the DMA transfer for the whole group is possible after the
conversion of the last channel of the group is finished.
3.10.
Range Comparator Function
The range comparator offers eight comparison groups with an upper and a lower threshold register each.
The 64 logical channels can be enabled for range comparison and assigned to one of the eight
comparators individually.
If range comparator is enabled for a logical channel, it provides two result flags:
−
Interrupt flags ADC12Bn_RCIRQ0 to 1.RCIRQ and ADC12Bn_CHSTAT0 to 63.RCIRQ, signaling
that the A/D conversion result is outside the range or inside the range ("inverted" operation, i.e.
ADC12Bn_CHCTRL0 to 63.RCINVSEL = "1").
−
Over threshold flags ADC12Bn_RCOTF0 to 1.RCOTF and ADC12Bn_CHSTAT0 to 63.RCOTF,
showing that the A/D conversion value exceeded the upper threshold in the case of outside range
detection.
Furthermore, each logical channel can be enabled to send an interrupt request to the CPU, if dedicated
flags ADC12Bn_RCIRQ0 to 1.RCIRQ63 to 0 and ADC12Bn_CHSTAT0 to 63.RCIRQ are set.
The range comparator can choose 12/8-bit mode by the full range comparator mode
(ADC12Bn_CTRL.FRCMD).
ADC12Bn_CTRL.FRCMD Description
"1" : 12-bit range comparator
ADC12Bn_FRCOL0 to 11/FRCOH0 to 11 are used for range comparator upper/lower threshold
value.
Selection of one of eight available range comparator threshold values for the logical channel is
configured by corresponding ADC12Bn_CHCTRL0 to 63.RCSEL[2:0] bit fields.
The upper/lower comparator compares the 12 bits, 10 bits or 8 bits of the A/D conversion result.
ADC12Bn_CTRL.RES[1:0] define this resolution.
− If 12-bit resolution (ADC12Bn_CTRL.RES[1:0] = "x0"): Compares the 12 bits of A/D conversion result.
− If 10-bit resolution (ADC12Bn_CTRL.RES[1:0] = "01"): Compares the 10 bits of A/D conversion result.
− If 8-bit resolution (ADC12Bn_CTRL.RES[1:0] = "11"): Compares the 8 bits of A/D conversion result.
"0" : 8-bit range comparator
ADC12Bn_RCOL0 to 7/RCOH0 to 7 are used for range comparator upper/lower threshold value.
Selection of one of eight available range comparator threshold values for the logical channel is
configured by corresponding ADC12Bn_CHCTRL0 to 63.RCSEL[2:0] bit fields.
The upper/lower comparator compares the upper 8 bits of the A/D conversion result.