Synchronizing the On-Chip Analog-to

Freescale Semiconductor
Application Note
Synchronizing the On-Chip
Analog-to-Digital Converter
on 56F80x Devices
Synchronization of the Internal Analog-to- Digital
Converter on 56F80x Devices to Internal and
External Events.
Daniel Malik
1.
Introduction
This Application Note describes the synchronization of the
56F80x on-chip Analog-to-Digital Converter (ADC) module to
internal and external events. The following sections show
examples of the typical ADC operation, settings needed for
achieving synchronization and other settings needed to operate
the ADC module.
2.
Advantages and Key Features
The Freescale 56F80x Digital Signal Controller (DSC) family is
well suited for digital motor control, combining the DSP’s
calculation capability with the MCU’s controller features on a
single chip. These devices offer many dedicated peripherals, such
as Pulse Width Modulation (PWM) unit, Analog-to-Digital
Converters (ADC), Timers, communication peripherals (SCI,
SPI, CAN), on-board Flash and RAM. Generally, all family
members are well-suited to motor control.
© Freescale Semiconductor, Inc., 2002, 2005. All rights reserved.
AN1933
Rev. 1, 11/2005
Contents
1. Introduction .............................................1
2. Advantages and Key Features ................1
3. Purpose of ADC Synchronization ..........4
3.1 Sources of Synchronization Events...... 4
3.2 ADC Synchronization to PWM in
Motor Control.......................................4
4. Description of Hardware Features ..........6
5. Examples of Synchronization Modes .....8
5.1 Periodic Sampling ................................ 8
5.2 Sampling Synchronous to PWM.......... 9
5.3 Synchronization of ADC to External
Events ................................................. 13
5.4 Using More than One Timer for More
Advanced Synchronization................. 13
6. Conclusion ............................................15
7. References .............................................15
Advantages and Key Features
A typical member of the family, the 56F805, provides the following peripheral blocks:
•
Two Pulse Width Modulator modules (PWMA & PWMB), each with six PWM outputs, three Current
Sense inputs, and four Fault inputs, fault tolerant design with deadtime insertion, supporting both
Center- and Edge- aligned modes
•
Twelve bit, Analog-to-Digital Convertors (ADCs), which support two simultaneous conversions with
8-pin multiplexed inputs; ADC can be synchronized by PWM Module
•
Two Quadrature Decoders, each with four inputs, or two additional Quad Timers
•
Two General Purpose Quad Timers totaling six pins; Timer C with two pins and Timer D with four
pins
•
CAN 2.0 A/B Module with 2-pin port used to transmit and receive
•
Two Serial Communication Interfaces, each with two pins (or four additional GPIO lines)
•
Serial Peripheral Interface (SPI), with configurable 4-pin port (or four additional GPIO lines)
•
Fourteen dedicated General Purpose I/O (GPIO) pins, 18 multiplexed GPIO pins
•
Computer Operating Properly (COP) Watchdog timer
•
Two dedicated external interrupt pins
•
External reset input pin for hardware reset
•
External reset output pin for system reset
•
JTAG/On-Chip Emulation (OnCETM) for unobtrusive, processor speed-independent debugging
•
Software-programmable, phase lock loop-based frequency synthesizer for the core clock .
•
Table 2-1. Memory Configuration
56F801
56F803
56F805
56F807
Program Flash
8188 x 16-bit
32252 x 16-bit
32252 x 16-bit
61436 x 16-bit
Data Flash
2K x 16-bit
4K x 16-bit
4K x 16-bit
8K x 16-bit
Program RAM
1K x 16-bit
512 x 16-bit
512 x 16-bit
2K x 16-bit
Data RAM
1K x 16-bit
2K x 16-bit
2K x 16-bit
4K x 16-bit
Boot Flash
2K x 16-bit
2K x 16-bit
2K x 16-bit
2K x 16-bit
The flexible PWM module, the 16-bit Quadrature Timer modules and the ADC module are especially useful in
motor control. The flexible hardware configuration enhances the efficiency of motor control.
The PWM module has the following features:
•
Three complementary PWM signal pairs, or six independent PWM signals
•
Features of complementary channel operation
•
Deadtime insertion
•
Separate top and bottom pulse width correction via current status inputs or software
•
Separate top and bottom polarity control
Synchronizing the On-Chip ADC on 56F80x Devices, Rev. 1
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Preliminary
•
Edge-aligned or center-aligned PWM signals
•
15 bits of resolution
•
Half-cycle reload capability
•
Integral reload rates from one to 16
•
Individual software-controlled PWM output
•
Programmable fault protection
•
Polarity control
•
20mA current sink capability on PWM pins
•
Write-protectable registers
The Quadrature Timer modules have the following features:
•
Each timer module consists of four 16-bit counters/timers
•
Count up/down
•
Counters are cascadable
•
Programmable count modulo
•
Max count rate equals peripheral clock/2 when counting external events
•
Max count rate equals peripheral clock when using internal clocks
•
Count once or repeatedly
•
Counters are preloadable
•
Counters can share available input pins
•
Each counter has a separate prescaler
•
Each counter has capture and compare capability
The ADC module has the following features:
•
12-bit resolution
•
Sampling rate up to 1.66 million samples per second1
•
Maximum ADC clock frequency is 5MHz with 200ns period
•
Single conversion time of 8.5 ADC clock cycles (8.5 x 200 ns = 1.7µs)
•
Additional conversion time of 6 ADC clock cycles (6 x 200 ns = 1.2µs)
•
Eight conversions in 26.5 ADC clock cycles (26.5 x 200 ns = 5.3µs) using simultaneous mode
•
Simultaneous or sequential sampling
•
Internal multiplexer to select two of eight inputs
•
Ability to sequentially scan and store up to eight measurements
•
Ability to simultaneously sample and hold two inputs
•
Optional interrupts at end of scan, if an out-of-range limit is exceeded or at zero crossing
•
Optional sample correction by subtracting a pre-programmed offset value
•
Signed or unsigned result
•
Single ended or differential inputs
1. Once in loop mode, the time between each conversion is 6 ADC clock cycles (1.2 µs). Using simultaneous conversion, two samples can be obtained in 1.2 µs. Samples per second is calculated according to 1.2 µs per two samples
or 1666666 samples per second.
Synchronizing the On-Chip ADC on 56F80x Devices, Rev. 1
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Preliminary
3
Purpose of ADC Synchronization
3.
Purpose of ADC Synchronization
Many applications require the analog-to-digital conversion to be started by a particular (usually repetitive)
event. An interrupt service routine can be used to handle the conversion process in cases if an interrupt can be
associated with an event. However this approach consumes processing power of the device and the exact time
when the analog input channel was sampled is not known accurately, because the interrupt latency time is
uncertain. On the other hand, if the ADC conversion process can be started by an independent hardware
mechanism, then the sampling time is known with a high degree of accuracy and device core processing time is
saved as well.
The 56F80x family of motor control devices offers very flexible means of triggering the ADC conversion
process in hardware, independent of the device core operation. It is capable of starting a conversion in response
to an internal or an external hardware event, where the latency time is not only deterministic to a high degree of
accuracy, but can also be deliberately chosen and changed on the fly.
3.1 Sources of Synchronization Events
In motor control, the timebase of the whole application is usually derived from a PWM and it is desirable to
synchronize ADC operations at the beginning of a PWM period. In many other applications, the timebase is
created by a timer instead of a PWM and it is then necessary to synchronize the ADC to an operation of a timer
peripheral. In some applications, the timebase is created by circuits and processes, which are external to the
device. In such a case, it is necessary to synchronize the ADC to an external signal.
Members of the 56F80x family are capable of performing all three modes of operation and the synchronization
signal for the ADC can be generated by:
•
PWM (internal sync signal)
•
Timer (internal event)
•
External signal
3.2 ADC Synchronization to PWM in Motor Control
The circuitry in Figure 3-1 is an example of the most commonly used power stage topology in motor control
applications. When controlling transistors by a PWM signal, the inductive load voltage and the current
waveforms can look as shown in Figure 3-2. The motor torque is a function of the electrical current, flowing
through individual motor phases and the measurement of the phase current is therefore an important feature for
almost all motor control applications. As seen in Figure 3-2, the phase current has a triangular waveform,
synchronous to the PWM operation. By synchronizing the phase current measurement with the PWM
operation, we can eliminate the need for filtration of the result. The result is a higher sample rate, which may
be needed for fast enough filtering. Otherwise it would be necessary to obtain a reasonably stable and precise
value. The figure also shows that the winding current equals the average current twice over the PWM period centers of TON and TOFF periods are the best moments to the sample winding currents in order to get precise
values.
Another good reason for synchronization of the measurement to a PWM operation in motion control systems is
the elimination of noise. Most of the electromagnetic noise, which is generated internally by motor control
applications, is originated in switching processes of semiconductor power switches (usually MOSFETs or
IGBTs). By synchronizing analog measurements to the PWM we can make sure that none of the measurements
will be performed during switching of the power semiconductors and the measurements will therefore be
unaffected by the generated noise.
Synchronizing the On-Chip ADC on 56F80x Devices, Rev. 1
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Preliminary
ADC Synchronization to PWM in Motor Control
+1/2 U
TPWM
DEADTIME
Motor
winding
TON TOFF
u
i
Load inductance acts like a low
pass filter to smooth current.
-1/2 U
Figure 3-1. Half Bridge Power Stage
average current
winding
current
one PWM period
+U/2
winding
voltage
TOFF
TON
-U/2
time
Figure 3-2. Applied PWM
Synchronizing the On-Chip ADC on 56F80x Devices, Rev. 1
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Preliminary
5
Description of Hardware Features
4.
Description of Hardware Features
Figure 4-1 shows the part of the device involved in ADC synchronization (please note that not all blocks are
present on all family members).
PWM
outputs
PWMA
PWMA sync output
ADCA sync input
Fault
inputs
TC2
in
PWM
outputs
TC3
in
ADCA
TC2
out
Analog
inputs
Vref
Timer C
Fault
inputs
PWMB
PWMB sync output
TC3
out
ADCB sync input
ADCB
Analog
inputs
Vref
I/O pins TC0 & TC1
Chip boundary
Figure 4-1. On-chip Synchronization Hardware Blocks
The heart of the ADC on-chip synchronization hardware features is the Quad Timer block C (see [1.] for
details). This timer block has only two I/O pins and the two remaining I/O channels are used for
synchronization signals. The internal structure of the Quad Timer C is shown in Figure 4-2. Note how the
PWM and the ADC blocks are connected to the timer structure - timer C2 and C3 inputs are provided with
synchronization signals from the PWMA and PWMB blocks, and the outputs are used to trigger the conversion
of ADCA and ADCB. The internal Timer input multiplexer architecture allows routing of signals from PWMA
and PWMB to any Timer channel.
A pulse occurs at PWMA and PWMB synchronization outputs for each reload of the respective PWM,
regardless of the state of the LDOK bit. When half-cycle reloads are enabled, the pulse can occur on the half
cycle. Details about PWM synchronization outputs are described in Figure 5-3 and Figure 5-4.
The Timer module processes the input signals from the PWM modules or external pins and triggers ADC
conversions. The usual function of the Timer is to insert a user-defined delay or to generate a periodic trigger.
The function provided by the Timer module is application-dependant and the most commonly used setups are
explained in the next section.
The ADCA and ADCB blocks will start the conversion process when a rising edge occurs at their respective
synchronization inputs (providing the SYNC bit in ADCR1 register is set and no conversion is in progress).
Synchronizing the On-Chip ADC on 56F80x Devices, Rev. 1
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Preliminary
ADC Synchronization to PWM in Motor Control
OFLAG
Timer C0
COUNTER
LOAD
HOLD
CAPTURE
COMPARE
COMPARE
CMP1
CMP2
Input MUX
DATA BUS
OFLAG
Timer C1
COUNTER
LOAD
HOLD
CAPTURE
COMPARE
COMPARE
CMP1
CMP2
DATA BUS
OFLAG
Timer C2
COUNTER
LOAD
HOLD
CAPTURE
COMPARE
COMPARE
CMP1
CMP2
DATA BUS
OFLAG
Timer C3
COUNTER
LOAD
HOLD
CAPTURE
COMPARE
COMPARE
CMP1
CMP2
DATA BUS
÷1 ... ÷128
I/O
MUX
IP Bus Clock I/O pin I/O pin
TC0
TC1
PWMA PWMB
Sync Sync
ADCA ADCB
Sync Sync
Figure 4-2. Internal Structure of Quad Timer C
Synchronizing the On-Chip ADC on 56F80x Devices, Rev. 1
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Preliminary
7
Examples of Synchronization Modes
5.
Examples of Synchronization Modes
The synchronization modes shown in this chapter are only a very small subset of all possible synchronization
setups. Great varieties of synchronization modes are possible due to a flexible hardware architecture, therefore
the user can select a setup best suitable for his particular application.
The most commonly used setups, which are described here, are:
•
Periodic sampling
•
Synchronization to PWM
•
Synchronization to external event
•
Advanced synchronization utilizing two timer channels
The setup of the ADC module is the same for all examples shown; they only differ in the setup of the timer and
the PWM peripherals. The ADC module is initialized to “triggered sequential” mode, the SYNC bit in ADCR1
is set to enable hardware triggering and the end-of-scan interrupt is enabled to acquire data from the result
registers in the interrupt service routine.
5.1 Periodic Sampling
This section describes the triggering of the ADC in order to digitize the analog input signal at an exact
user-defined frequency. In this mode timer C2 is running freely and triggers the ADC conversion by toggling
its output on every compare event.
Value
0
0
1
12
11
10
9
8
7
6
5
4
0
1
1
3
2
1
0
0
1
1
Toggle output
on compare
13
Count down
14
Reinitialize
on compare
15
Count rising
edges
Bit
Count
repeatedly
The setup of the timer is shown in Figure 5-1 - the timer is counting down, starting from the value stored in the
Load Register (TMRC2_LOAD), down to the value stored in the Compare Register 2 (TMRC2_CMP2). In an
usual setup, the Compare Register 2 will be loaded with 0 and the Load Register will hold one half of the
sample period length.
Figure 5-1. Timer C2 Control Register (TMRC2_CTRL)
The ADCA conversion sequence is triggered on every rising edge of the Timer C2 output and samples are
converted. The conversion process takes 8.5 ADC clock cycles for the first sample and 6 ADC clock cycles for
any consecutive samples in the acquisition sequence.
Note that the start of conversions is aligned to the next rising edge of the ADC Clock - at a maximum
frequency of 5 MHz, the maximum delay is 200 ns. The timing is shown in Figure 5-2.
Synchronizing the On-Chip ADC on 56F80x Devices, Rev. 1
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Preliminary
Sampling Synchronous to PWM
Timer C2 value
Time C2 output
ADC Clock
ADC
conversion
8.5+6•(#samples -1)
ADC Clock cycles
Figure 5-2. Timing of Periodic Sampling
5.2 Sampling Synchronous to PWM
The simplest form of synchronizing measurements to PWM operation is running one acquisition sequence per
PWM period. In this mode the timebase is provided by the PWM peripheral instead of the Timer. There are
two basic modes of operation of the PWM peripheral: Center-Aligned and Edge-Aligned. Differences between
these modes and the timing of the synchronization output are shown in Figure 5-3 and Figure 5-4. A
synchronization pulse appears at the output of the PWM block for each reload of the PWM, regardless of the
state of the LDOK bit. Note that the synchronization signal is internal to the chip. It is not directly bonded out
to any pin, however, it can be observed indirectly through the operation of the timer with a dedicated
input/output pin (Timer C0 or Timer C1).
5
PWM Counter 4
value 3
(Modulus = 5) 2
1
PWM Value = 0
PWM Value = 1
PWM Value = 2
PWM Value = 3
PWM Value = 4
PWM Value = 5
PWM Sync output
(reload every cycle)
PWM Sync output
(reload every 2 cycles)
Figure 5-3. Timing of PWM Signals in Edge-Aligned Mode
Synchronizing the On-Chip ADC on 56F80x Devices, Rev. 1
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Preliminary
9
Examples of Synchronization Modes
5
4
PWM Counter 3
value 2
(Modulus = 5) 1
0
PWM Value = 0
PWM Value = 1
PWM Value = 2
PWM Value = 3
PWM Value = 4
PWM Value = 5
PWM Sync output
(reload every half cycle)
PWM Sync output
(reload every cycle)
Figure 5-4. Timing of PWM Signals in Center-Aligned Mode
Note that the PWM outputs are delayed by one IP Bus Clock with respect to the PWM counter.
Value
1
1
0
12
11
10
9
8
7
6
5
4
0
1
1
3
2
1
0
1
0
1
Output set on
compare, cleared
on secondary
source input edge
13
Count down
14
Reinitialize
on compare
15
Edge of
secondary source
triggers primary
source count till
compare
Bit
Count
repeatedly
This mode requires the Timer C2 to act as a programmable delay line. After detection of the secondary input
rising edge (falling edge if IPS bit in TMRC2_SCR register is set), the timer output is cleared and the timer
starts counting. When the timer value reaches the pre-programmed compare value a compare event occurs, the
timer stops counting, reloads its initial value from the Load Register and the output is set. The setup of the
timer is shown in Figure 5-5.
Figure 5-5. Timer C2 Control Register (TMRC2_CTRL)
The assertion of the Timer C2 output triggers the ADCA conversion sequence, samples are taken and stored in
Result Registers (the conversion process takes 8.5 ADC Clock cycles for the first sample and 6 ADC Clock
cycles for any consecutive sample in the acquisition sequence). The timing shown in Figure 5-6 assumes that
the PWM is running in Center-Aligned mode and that both the PWM and the Timer peripherals are clocked by
the IPBus Clock with prescaler of 1. The ADC conversion timing is shown only for the case where the IPS bit
is set. Please note that the start of ADC the conversion process is aligned to the next rising edge of the ADC
Clock (not shown in the figure) - at a maximum frequency of 5 MHz the maximum delay is 200 ns.
Synchronizing the On-Chip ADC on 56F80x Devices, Rev. 1
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Preliminary
Sampling Synchronous to PWM
Please also note, that, due to the synchronous architecture used for the Timer peripheral and for the signal
propagation delay, the Timer will receive the synchronization signal one clock cycle after reloading the PWM
module (i.e. one clock cycle after the center of the PWM output pulse in Center-Aligned mode).
The whole situation becomes more complicated when the output pulses are shortened by deadtime. Figure 5-7
shows the timing in such a situation. At the top of the figure, the PWM counter and PWM synchronization
output are shown. Below you can see an example of the complementary PWM outputs for a PWM value of 2.
Up to now the situation is the same as in Figure 5-4. When deadtime insertion is enabled, all output rising
edges are delayed (assuming outputs are active high).
5
4
PWM Counter 3
Value 2
(Modulus = 5) 1
0
IPBus Clock
IPS bit set
IPS bit cleared
PWM Sync output
(reload every cycle)
Timer C2 counter
value
(Load value of 5)
Timer C2 output
Timer C2 counter
value
(Load value of 5)
Timer C2 output
ADC Conversion
(aligned to ADC CLK)
Figure 5-6. Timing of Sampling Synchronous to PWM
Let’s now consider the whole motor control system, including optoisolation, transistor drivers and the power
transistors themselves. All these components cause some signal delays, so the voltage waveform at the motor is
shifted by a certain delay.
Let’s now assume that the application requires measurement of currents, using shunt resistors, connected
between the low side power transistor and the negative DC Bus terminal. Therefore we need to measure the
currents only when the low side transistor is in ON state. The best way to achieve such a measurement is to
schedule the ADC conversion to take place as near as possible of to the middle of the bottom transistor
conduction pulse as possible - this optimum point is marked in Figure 5-7 with red circles. Now we need to
calculate the desired delay for the delay line, implemented by the Timer C2.
Synchronizing the On-Chip ADC on 56F80x Devices, Rev. 1
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Preliminary
11
Examples of Synchronization Modes
As seen in Figure 5-7, the center of the PWM top transistor output signal, with dead time deactivated, is at the
reload point. The center of the PWM bottom transistor output signal is then at a T ⁄ 2 distance from the reload
point, where T is the PWM period. However the timer starts counting one clock cycle after the reload point.
The time delay between counter start and center of the PWM bottom transistor signal is therefore
T ⁄ 2 – t PWM , where t PWM is the PWM clock period.
When deadtime is enabled, it can be seen that the center point is shifted by half of the deadtime. The center of
the PWM bottom transistor output signal is therefore T ⁄ 2 – tPWM + T D ⁄ 2 , where T D is the deadtime.
The ADC sampling process is about 3 ADC clock cycles long and the start of the ADC conversion process is
delayed up to the next rising edge of the ADC clock. Therefore it is necessary to subtract 2 ADC clock cycles
to achieve an even distribution of the sampling point around the desired center of the bottom transistor pulse.
The last thing to add to the whole external hardware is the delay time T S - combined optoisolation, driver
and transistor delay. The final formula for the Timer delay is therefore:
Timer Delay = T ⁄ 2 – t PWM + T D ⁄ 2 – 2t ADC + T S
5
4
PWM Counter 3
Value 2
(Modulus = 5) 1
0
PWM
reload
PWM
reload
Deadtime=2 Deadtime=0
PWM Sync output
(reload every cycle)
PWM Value = 2
Complementary
channel
PWM Value = 2
Complementary
channel
Signal shift caused
by optoisolation,
driver circuits and
power transistors
Timer C2 output
ADC Conversion
(aligned to ADC CLK)
= ADC Sampling process
= Deadtime
Figure 5-7. Timing of Sampling Synchronous to PWM with Deadtime
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Preliminary
Using More than One Timer for More Advanced Synchronization
It is now easy to convert the delay time to the Load Register value:
T ⁄ 2 – t PWM + T D ⁄ 2 – 2t ADC + T S
Timer Load Register value = ----------------------------------------------------------------------------------- – 1
t Timer
Note that for a value of 0 in the Load Register the Timer produces a delay of 1 clock cycle (hence the
subtraction of 1 in above equation).
This synchronization mode is fully autonomous and does not require any software interference. Therefore it is
well suited for a wide range of applications.
5.3 Synchronization of ADC to External Events
The previous section described the ADC synchronization to a signal derived from the PWM module. The same
principle applies to an ADC synchronization to an external signal. The setup is different only in that the
synchronization signal from an external pin (TC0 or TC1) is used instead of the PWM signal (TMRCx_CTRL
Register).
5.4 Using More than One Timer for More Advanced Synchronization
The Timer block C contains 4 timers and more than one timer unit can be utilized to achieve complex
synchronization algorithms. In Section 5.2 we have seen how to perform one ADC acquisition sequence per
PWM reload period. Let’s assume that we would like to perform several series of ADC acquisition sequences
to acquire more data points.
To achieve this goal we need to use two timer units. Timer C1 is setup to act as a delay line and synchronizes
the whole process of PWM reloads. Timer C2 is setup to count only when the output of Timer C1 is low and
generates a synchronizations signal for the ADC. The whole process is shown in Figure 5-8.
Synchronizing the On-Chip ADC on 56F80x Devices, Rev. 1
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Preliminary
13
Examples of Synchronization Modes
PW M counter
PW M sync output
PW M generator
outputs
D eadtim e / 2
PW M output 0
C om plem entary
PW M output
D eadtim e
winding voltage
@ Positive current
winding current
t5
TC 1 output
t1
t2
t3
t4
TC 2 output
AD C conversion
AD C ISR
Figure 5-8. Example of a Complex Synchronizations Setup
After the PWM module has generated the synchronization signal, Timer C1 starts counting and forces its
output low. This makes Timer C2 start counting and, once Timer C2 reaches its compare value (time t1), it sets
its output triggering ADC conversion. Timer C2 will load a new counter value from its Load Register
(corresponding to time t2) and continue counting. After the ADC has finished the acquisition sequence, an
ADC interrupt is issued and the interrupt service routine is called. This routine picks up results from the ADC
Result Registers and reprograms Timer C2 (Timer C2 output is reset and a new value is stored in the Load
Register - corresponds to timer t3). After Timer C2 has reached the compare value once again (timer t2 is
over), the ADC conversion is triggered and the whole process repeats.
Time t5 equals t1+t2+t3+t4 in our example; therefore at the end of the acquisition series, the Timer C1 output
is set and Timer C2 stops counting. After the ADC finishes the last conversion, the interrupt service routine is
called for the last time in the series and prepares Timer C2 for the next series (Counter Register is loaded with
a value corresponding to time t1 and the Load Register is loaded with a value corresponding to time t2).
Synchronizing the On-Chip ADC on 56F80x Devices, Rev. 1
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Preliminary
Using More than One Timer for More Advanced Synchronization
The number of acquisition sequences (performed in one series) and the delays between them (times t1, t2,...)
can be freely chosen to fit in the application.
The execution of equidistant acquisition sequences (i.e. times t2, t3,... are equal) can be achieved by
pre-programming the timer Load Register with a constant value. This simplifies the interrupt service routine
because the user does not need to handle the Load Register updates.
6.
Conclusion
The new Freescale chips - 56F80x - offer exceptional hardware features with high degree of flexibility. The
56F80x on-chip Analog-to-Digital converter (ADC) module can be synchronized to internal and external
events with zero processing overhead. The on-chip timer architecture offers a high versatility, which makes the
part suitable for a wide range of applications, starting from servos and control of a large variety of motor types,
power inverter and converter applications up to the control of actuators or modems.
7.
References
[1.] 56F80x 16-bit Digital Signal Controller User’s Manual, DSP56F801-7UM, Freescale Semiconductor,
Inc.
[2.] 56F80x MC PWM Module in Motor Control Applications, AN1905, Freescale Semiconductor, Inc.
Synchronizing the On-Chip ADC on 56F80x Devices, Rev. 1
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Preliminary
15
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