
Configurable Enhanced Modular IO Subsystem (eMIOS200)
MPC5644A Microcontroller Reference Manual, Rev. 6
668
Freescale Semiconductor
22.5.1.1.5
Input period measurement (IPM) mode
The IPM mode (MODE[0:6] = 0000101) allows the measurement of the period of an input signal by
capturing two consecutive rising edges or two consecutive falling edges. Successive input captures are
done on consecutive edges of the same polarity. The edge polarity is defined by the EDPOL bit in the
EMIOS_CCR[n].
When the first edge of selected polarity is detected, the selected time base is latched into the registers A2
and B2, and the data previously held in register B2 is transferred to register B1. On this first capture the
FLAG line is not set, and the values in registers B1 is meaningless. On the second and subsequent captures,
the FLAG line is set and data in register B2 is transferred to register B1.
When the second edge of the same polarity is detected, the counter bus value is latched into registers A2
and B2, the data previously held in register B2 is transferred to data register B1 and to register A1. The
FLAG bit is set to indicate the start and end points of a complete period have been captured. This sequence
of events is repeated for each subsequent capture. Registers EMIOS_CADR[n] and EMIOS_CBDR[n]
return the values in register A2 and B1, respectively.
In order to allow coherent data, reading EMIOS_CADR[n] forces A1 content be transferred to B1 register
and disables transfers between B2 and B1. These transfers are disabled until the next read of the
EMIOS_CBDR[n]. Reading EMIOS_CBDR[n] forces A1 content to be transferred to B1 and re-enables
transfers from B2 to B1, to take effect at the next edge capture.
The input pulse period is calculated by subtracting the value in B1 from A2.
shows how the channel can be used for input period measurement.
Figure 22-21. Input Period Measurement example
describes the A1 and B1 register updates when EMIOS_CADR[n] and EMIOS_CBDR[n]
read operations are performed. When EMIOS_CADR[n] read occurs the content of A1 is transferred to B1
thus providing coherent data in A2 and B1 registers. Transfers from B2 to B1 are then blocked until
EMIOS_CBDR[n] is read. After EMIOS_CBDR[n] is read, register A1 content is transferred to register
B1 and the transfers from B2 to B1 are re-enabled to occur at the transfer edges, which is the leading edge
in the
example.
selected counter bus 0x000500
0x001000
0x001100
0x001250
0x001525
0x0016A0
A2(captured) value
2
A1 value
B2 (captured) value
0xxxxxxx
0x001000
0x001250
0xxxxxxx
0x001000
0x001250
0x0016A0
0xxxxxxx
0x001000
0x001250
0x0016A0
Input signal
1
EDPOL = 1
FLAG pin register
Notes: 1. After input filter
2. CADR[n] = A2
3. CBDR[n] = B1
A
A
A
B1 value
3
0xxxxxxx
0x001000
0x001250
Содержание MPC5644A
Страница 2: ...MPC5644A Microcontroller Reference Manual Rev 6 2 Freescale Semiconductor...
Страница 24: ...MPC5644A Microcontroller Reference Manual Rev 6 24 Freescale Semiconductor...
Страница 26: ...MPC5644A Microcontroller Reference Manual Rev 6 26 Freescale Semiconductor...
Страница 52: ...Introduction MPC5644A Microcontroller Reference Manual Rev 6 52 Freescale Semiconductor...
Страница 56: ...Memory Map MPC5644A Microcontroller Reference Manual Rev 6 56 Freescale Semiconductor...
Страница 130: ...Device Performance Optimization MPC5644A Microcontroller Reference Manual Rev 6 130 Freescale Semiconductor...
Страница 204: ...Multi Layer AHB Crossbar Switch XBAR MPC5644A Microcontroller Reference Manual Rev 6 204 Freescale Semiconductor...
Страница 212: ...Peripheral Bridge PBRIDGE MPC5644A Microcontroller Reference Manual Rev 6 212 Freescale Semiconductor...
Страница 558: ...System Integration Unit SIU MPC5644A Microcontroller Reference Manual Rev 6 558 Freescale Semiconductor...
Страница 582: ...Frequency modulated phase locked loop FMPLL MPC5644A Microcontroller Reference Manual Rev 6 582 Freescale Semiconductor...
Страница 766: ...Enhanced Time Processing Unit eTPU2 MPC5644A Microcontroller Reference Manual Rev 6 766 Freescale Semiconductor...
Страница 1228: ...Decimation Filter MPC5644A Microcontroller Reference Manual Rev 6 1228 Freescale Semiconductor...
Страница 1236: ...System Information Module and Trim SIM MPC5644A Microcontroller Reference Manual Rev 6 1236 Freescale Semiconductor...
Страница 1250: ...Cyclic Redundancy Checker CRC Unit MPC5644A Microcontroller Reference Manual Rev 6 1250 Freescale Semiconductor...
Страница 1336: ...Deserial Serial Peripheral Interface DSPI MPC5644A Microcontroller Reference Manual Rev 6 1336 Freescale Semiconductor...
Страница 1388: ...Enhanced Serial Communication Interface ESCI MPC5644A Microcontroller Reference Manual Rev 6 1388 Freescale Semiconductor...
Страница 1440: ...FlexCAN Module MPC5644A Microcontroller Reference Manual Rev 6 1440 Freescale Semiconductor...
Страница 1624: ...FlexRay Communication Controller FlexRay MPC5644A Microcontroller Reference Manual Rev 6 1624 Freescale Semiconductor...
Страница 1670: ...JTAG Controller JTAGC MPC5644A Microcontroller Reference Manual Rev 6 1670 Freescale Semiconductor...
Страница 1692: ...Nexus Port Controller NPC MPC5644A Microcontroller Reference Manual Rev 6 1692 Freescale Semiconductor...
Страница 1701: ...Development Trigger Semaphore DTS MPC5644A Microcontroller Reference Manual Rev 6 Freescale Semiconductor 1701...
Страница 1702: ...Development Trigger Semaphore DTS MPC5644A Microcontroller Reference Manual Rev 6 1702 Freescale Semiconductor...