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Enhanced Queued Analog-to-Digital Converter (EQADC)
MPC5644A Microcontroller Reference Manual, Rev. 6
1154
Freescale Semiconductor
Figure 25-94. RSD Adder
25.6.11.1.4
Variable Gain Amplification (VGA) for Pre-gain
The VGA starts after sampling completes. It is enabled by a 2-bit signal PRE_GAIN described in
Section 25.5.3.6, Alternate Configuration 1-8 Control Registers (ADC_ACR1-8)
.
The ADC takes 2, 8, 64 or 128 clock cycles to do sampling which is selected by the LST[0:1] field in the
conversion command message. After the sampling, if 2x VGA is enabled, there is a 2x gain stage without
comparison before the regular conversion cycles. When 4x VGA is enabled, there are the 2x gain stage
without comparison by 2 times before the normal conversion processing.
25.7
Initialization/Application information
25.7.1
Multiple queues control setup example
This section provides an example of how to configure multiple CQueues.
describes how each
CQueue can be used for a different application. Also documented in this section are general guidelines on
how to initialize the on-chip ADCs and the external device, and how to configure the CQueues and the
EQADC.
Table 25-75. Application of Each CQueue
CQueue
Number
CQueue Type
Running Speed
Number of
Contiguous
Conversions
Example
0
Very fast burst
time-based CQueue
every 2
s for 200
s;
pause for 300
s and then
repeat
2
Injector current profiling
1
Fast
hardware-triggered
CQueue
every 900
s
3
Current sensing of PWM
controlled actuators
2
Fast repetitive
time-based CQueue
every 2 ms
8
Throttle position
a13
b12 a12
b11 a11
b10 ..
.. ...
... a3
b2 a2
b1
------------------------------------------
s12 s11 s10 ... ... s2 s1
carry
+
Summary of Contents for MPC5644A
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