Analog Input on
Channel Ax
Analog Input on
Channel Bv
ADC Clock
Sample and Hold
SH Pulse
t
SH
t
dschA0_n
t
dschB0_n
t
dschB0_n+1
Sample n
Sample n+1
Sample n+2
t
dschA0_n+1
t
d(SH)
ADC Event Trigger from EV
or Other Sources
SMODE Bit
TMS320F2810, TMS320F2811, TMS320F2812
TMS320C2810, TMS320C2811, TMS320C2812
SPRS174T –APRIL 2001–REVISED MAY 2012
www.ti.com
6.30.7 Simultaneous Sampling Mode (Dual-Channel) (SMODE = 1)
In simultaneous mode, the ADC can continuously convert input signals on any one pair of channels
(A0/B0 to A7/B7). The ADC can start conversions on event triggers from the Event Managers (EVA/EVB),
software trigger, or from an external ADCSOC signal. If the SMODE bit is 1, the ADC will do conversions
on two selected channels on every Sample/Hold pulse. The conversion time and latency of the Result
register update are explained below. The ADC interrupt flags are set a few SYSCLKOUT cycles after the
Result register update. The selected channels will be sampled simultaneously at the falling edge of the
Sample/Hold pulse. The Sample/Hold pulse width can be programmed to be 1 ADC clock wide (minimum)
or 16 ADC clocks wide (maximum).
NOTE
In Simultaneous Mode, the ADCIN channel pair select has to be A0/B0, A1/B1, ..., A7/B7,
and not in other combinations (such as A1/B3, and so forth).
Figure 6-42. Simultaneous Sampling Mode Timing
Table 6-49. Simultaneous Sampling Mode Timing
AT 25-MHz
SAMPLE n SAMPLE n + 1 ADC CLOCK, REMARKS
t
c(ADCCLK)
= 40 ns
Delay time from event
t
d(SH)
2.5t
c(ADCCLK)
trigger to sampling
Sample/Hold width/ Acqps value = 0–15
t
SH
(1 + Acqps) * t
c(ADCCLK)
40 ns with Acqps = 0
Acquisition Width ADCTRL1[8:11]
Delay time for first
t
d(schA0_n)
result to appear in 4t
c(ADCCLK)
160 ns
Result register
Delay time for first
t
d(schB0_n)
result to appear in 5t
c(ADCCLK)
200 ns
Result register
Delay time for
successive results to
t
d(schA0_n+1)
(3 + Acqps) * t
c(ADCCLK)
120 ns
appear in Result
register
Delay time for
successive results to
t
d(schB0_n+1)
(3 + Acqps) * t
c(ADCCLK)
120 ns
appear in Result
register
148 Electrical Specifications Copyright © 2001–2012, Texas Instruments Incorporated
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