as5040 austriamicrosystems, as5040 Datasheet - Page 9

• Manufacturer Part Number: as5040
• Description: 10-bit Programmable Magnetic Rotary Encoder
• Manufacturer: austriamicrosystems

AS5040 10-BIT PROGRAMMABLE MAGNETIC ROTARY ENCODER
5
5.1
If CSn changes to logic low, Data Out (DO) will change
from high impedance (tri-state) to logic high and the
read-out will be initiated.
Data Content:
Revision 1.8
CLK
CSn
DO
D9:D0 absolute angular position data (MSB is
clocked out first)
OCF (Offset Compensation Finished), logic high
indicates the finished Offset Compensation Algorithm.
For fast startup, this bit may be polled by the external
microcontroller. As soon as this bit is set, the AS5040
has completed the startup and the data is valid (see
Table 4)
COF (Cordic Overflow), logic high indicates an out of
range error in the CORDIC part. When this bit is set,
the data at D9:D0 is invalid. The absolute output
maintains the last valid angular value.
This alarm may be resolved by bringing the magnet
within the X-Y-Z tolerance limits.
LIN (Linearity Alarm), logic high indicates that the
input field generates a critical output linearity.
When this bit is set, the data at D9:D0 may still be
After a minimum time t
output shift register with the first falling edge of
CLK.
Each subsequent rising CLK edge shifts out one bit
of data.
The serial word contains 16 bits, the first 10 bits are
the angular information D[9:0], the subsequent 6 bits
contain system information, about the validity of
data such as OCF, COF, LIN, Parity and Magnetic
Field status (increase/decrease) .
A subsequent measurement is initiated by a log.
“high” pulse at CSn with a minimum duration of t
10-bit Absolute Angular Position Output
t
Synchronous Serial Interface (SSI)
DO active
t
CLK FE
T
t
DO valid
CLK / 2
1
D9
CLK FE,
D8
D7
data is latched into the
Figure 5: Synchronous serial interface with absolute angular position data
D6
Angular Position Data
D5
D4
CSn.
D3
www.austriamicrosystems.com
8
D2
D1
MagINCn, (Magnitude Increase) becomes HIGH, when
the magnet is pushed towards the IC, thus the magnetic
field strength is increasing.
MagDECn, (Magnitude Decrease) becomes HIGH, when
the magnet is pulled away from the IC, thus the magnetic
field strength is decreasing.
Both signals HIGH indicate a magnetic field that is out of
the allowed range (see Table 3).
Table 3: Magnetic magnitude variation indicator
Note: Pins 1 and 2 (MagINCn, MagDECn) are open drain
outputs and require external pull-up resistors. If the
magnetic field is in range, both outputs are turned off.
The two pins may also be combined with a single pull-up
resistor. In this case, the signal is high when the
magnetic field is in range. It is low in all other cases (see
Table 3).
Even Parity bit for transmission error detection of bits
1…15 (D9…D0, OCF, COF, LIN, MagINCn, MagDECn)
INCn
Mag
D0
0
0
1
1
used, but can contain invalid data. This warning may
be resolved by bringing the magnet within the X-Y-Z
tolerance limits.
OCF
DECn
Mag
0
1
0
1
COF
Status Bits
LIN
Description
No distance change
Magnetic Input Field OK (in range)
Distance increase: Pull-function. This state
is dynamic, it is only active while the magnet
is moving away from the chip in Z-axis
Distance decrease: Push- function. This
state is dynamic, it is only active while the
magnet is moving towards the chip in Z.-
axis.
Magnetic Input Field invalid – out of range:
too large, too small (missing magnet)
M ag
IN C
D EC
M a g
16
Even
PAR
t
DO Tristate
t
CSn
t
CLK FE
Page 9 of 27
1
D9