Manchester Data Encoding; Operation At Low V; Bp Or Low Vdd; Operation At High V - Analog Devices ADXL180 iMEMS Manual

ADXL180

MANCHESTER DATA ENCODING

To encode data within the current modulation, the ADXL180
uses Manchester encoding. Manchester encoding works on the
principle of transitions representing binary 1s and 0s, as shown
in Figure 8. Manchester encoding uses a set of predefined start
bits to transmit the clocking within each message, see Figure 9.
The pattern of the start bits allows the receiver to synchronize
itself to the bit stream. These start bits are user selectable.
START BITS
LOGIC 1
I
SIG
BUS
CURRENT
I
IDLE
Figure 8. Manchester-1, Start Bits and Phase
START BITS
LOGIC 0
I
SIG
BUS
CURRENT
I
IDLE
Figure 9. Manchester-2, Bit Coding
LOGIC 0 LOGIC 0 LOGIC 1
LOGIC 0 LOGIC 1
LOGIC 0
Table 6. MAN Options
Manchester
MAN Coding
0 Manchester-1
(Default)
1 Manchester-2
The phase of the Manchester encoded data can be selected via
a bit in the configuration registers. See Figure 8 and Figure 9
for details. The configuration bit that sets the phase of the Man-
chester encoder also sets the value of the two start bits. The start
bits are 1, 0 for Manchester-1 and 0, 0 for Manchester-2. For
phase and start bit information, see Table 6.

OPERATION AT LOW V

The ADXL180 monitors its internal regulator voltage to ensure
proper operation. If the bus voltage drops, or the internal regu-
lator voltage drops below the V
resets. See the Voltage Regulator Monitor Reset Operation
section.

OPERATION AT HIGH V

If the regulator pin detects a high voltage, such as from a
short or leakage condition, the ADXL180 detects an error.
See the Voltage Regulator Monitor Reset Operation section
for more details.
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Start
Bits Logic 0 Logic 1
1, 0 Falling edge Rising edge
0, 0 Rising edge Falling edge
OR LOW V
BP DD
reset threshold, the device
PUR
DD