SD16_A Operation
28-17
SD16_A
28.2.10
Conversion Operation Using Preload
When multiple channels are grouped the SD16PREx registers can be used to
delay the conversion time frame for each channel. Using SD16PREx, the
decimation time of the digital filter is increased by the specified number of f
M
clock cycles and can range from 0 to 255. Figure 28−10 shows an example
using SD16PREx.
Figure 28−10. Conversion Delay using Preload − Example
Conversion
32
SD16OSRx = 32
Load SD16PREx:
SD16PREx = 8
Preload
applied
Time
Delayed Conversion
40
Delayed Conversion
Result
Conversion
32
f M cycles:
The SD16PREx delay is applied to the beginning of the next conversion cycle
after being written. The delay is used on the first conversion after SD16SC is
set and on the conversion cycle following each write to SD16PREx. Following
conversions are not delayed. After modifying SD16PREx, the next write to
SD16PREx should not occur until the next conversion cycle is completed,
otherwise the conversion results may be incorrect.
The accuracy of the result for the delayed conversion cycle using SD16PREx
is dependent on the length of the delay and the frequency of the analog signal
being sampled. For example, when measuring a DC signal, SD16PREx delay
has no effect on the conversion result regardless of the duration. The user
must determine when the delayed conversion result is useful in their
application.
Figure 28−11 shows the operation of grouped channels 0 and 1. The preload
register of channel 1 is loaded with zero resulting in immediate conversion
whereas the conversion cycle of channel 0 is delayed by setting
SD16PRE0 = 8. The first channel 0 conversion uses SD16PREx = 8, shifting
all subsequent conversions by 8 f
M
clock cycles.
Summary of Contents for MSP430x4xx Family
Page 1: ...MSP430x4xx Family 2007 Mixed Signal Products User s Guide SLAU056G ...
Page 2: ......
Page 6: ...vi ...
Page 114: ...3 76 RISC 16 Bit CPU ...
Page 304: ...5 20 FLL Clock Module ...
Page 340: ...7 8 Supply Voltage Supervisor ...
Page 348: ...8 8 16 Bit Hardware Multiplier ...
Page 372: ...9 24 32 Bit Hardware Multiplier ...
Page 400: ...10 28 DMA Controller ...
Page 428: ...13 10 Basic Timer1 ...
Page 466: ...15 24 Timer_A ...
Page 522: ...17 30 USART Peripheral Interface UART Mode ...
Page 544: ...18 22 USART Peripheral Interface SPI Mode ...
Page 672: ...23 12 Comparator_A ...
Page 692: ...24 20 LCD Controller ...
Page 746: ...26 28 ADC12 ...