ATSAM3U-EK Atmel, ATSAM3U-EK Datasheet - Page 776

• Manufacturer Part Number: ATSAM3U-EK
• Description: KIT EVAL FOR AT91SAM3U CORTEX
• Manufacturer: Atmel
• Type: MCUr

Specifications of ATSAM3U-EK

• Contents: Board
• Processor To Be Evaluated: SAM3U
• Data Bus Width: 32 bit
• Interface Type: RS-232, USB
• Operating Supply Voltage: 3 V
• Silicon Manufacturer: Atmel
• Core Architecture: ARM
• Core Sub-architecture: Cortex - M3
• Silicon Core Number: SAM3U4E
• Silicon Family Name: SAM3U
• Kit Contents: Board CD Docs
• Rohs Compliant: Yes
• For Use With/related Products: AT91SAM3U
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

36.6.14.5
776
776
SAM3U Series
SAM3U Series
Speed Measurement
In parallel, the number of edges are accumulated on timer/counter channel 0 and can be read on
the TC_CV0 register.
Therefore, the accurate position can be read on both TC_CV registers and concatenated to form
a 32-bit word.
The timer/counter channel 0 is cleared for each increment of IDX count value.
Depending on the quadrature signals, the direction is decoded and allows to count up or down in
timer/counter channels 0 and 1. The direction status is reported on TC_QISR register.
When SPEEDEN is set in TC_BMR register, the speed measure is enabled on channel 0.
A time base must be defined on channel 2 by writing the TC_RC2 period register. Channel 2
must be configured in waveform mode (WAVE bit field set) in TC_CMR2 register. WAVSEL bit
field must be defined with 0x10 to clear the counter by comparison and matching with TC_RC
value. ACPC field must be defined at 0x11 to toggle TIOA output.
This time base is automatically fed back to TIOA of channel 0 when QDEN and SPEEDEN are
set.
Channel 0 must be configured in capture mode (WAVE = 0 in TC_CMR0). ABETRG bit field of
TC_CMR0 must be configured at 1 to get TIOA as a trigger for this channel.
EDGTRG can be set to 0x01, to clear the counter on a rising edge of the TIOA signal and LDRA
field must be set accordingly to 0x01, to load TC_RA0 at the same time as the counter is cleared
(LDRB must be set to 0x01). As a consequence, at the end of each time base period the differ-
entiation required for the speed calculation is performed.
The process must be started by configuring the TC_CR register with CLKEN and SWTRG.
The speed can be read on TC_RA0 register in TC_CMR0.
Channel 1 can still be used to count the number of revolutions of the motor.
6430D–ATARM–25-Mar-11
6430D–ATARM–25-Mar-11