AMIS-30624 Datasheet, PDF (20/56 Pages) AMI SEMICONDUCTOR – I2C Microstepping Motordriver

AMIS-30624 I²C Microstepping Motordriver
Data Sheet
15.1.4. Hardwired Address HW
In Figure 10 a simplified schematic diagram is shown of the HW comparator circuit.
The HW pin is sensed via two switches S_TOP and S_BOT. The DriveHS and DriveLS control lines are alternatively closing S_TOP and S_BOT ,
connecting HW pin with a current to resistor converter. Closing S_TOP (DriveHS = 1) will sense a current to GND. In that case the top IÆ
R converter output is low, via the closed passing switch S_{PASS_T} this signal is fed to the “R” comparator which output HW_Cmp is high.
Closing bottom switch S_BOT (DriveLS = 1) will sense a current to VBAT. The corresponding IÆ R converter output is low and via S_{PASS_B}
fed to the comparator. The output HW_Cmp will be high.
IÎ R
S_{PASS_T}
HW ^S_TOP
S_BOT
DriveHS
DriveLS
LOGIC
64 ms
Debouncer
State
High
Low
Float
1 = R2GND 2 = R2VBAT 3 = OPEN
IÎ R
S_{PASS_B}
R_th
"R"-Comp
COMP
32 µs
Debouncer
HW_Cmp
Figure 10: Simplified Schematic Diagram of the HW Comparator
PC20060926.1
Three cases can be distinguished (see also Figure 10):
- HW is connected to ground: R2GND or Drawing 1
- HW is connected to VBAT: R2VBAT or Drawing 2
- HW is floating: OPEN or Drawing 3
Table 15: State Diagram of the HW Comparator
Previous State DriveLS DriveHS HW_Cmp
Float
1
0
0
Float
1
0
1
Float
0
1
0
Float
0
1
1
Low
1
0
0
Low
1
0
1
Low
0
1
0
Low
0
1
1
High
1
0
0
High
1
0
1
High
0
1
0
High
0
1
1
New State
Float
High
Float
Low
Low
High
Float
Low
Float
High
High
Low
Condition
R2GND or OPEN
R2VBAT
R2VBAT or OPEN
R2GND
R2GND or OPEN
R2VBAT
R2VBAT or OPEN
R2GND
R2GND or OPEN
R2VBAT
R2VBAT or OPEN
R2GND
Drawing
1 or 3
2
2 or 3
1
1 or 3
2
2 or 3
1
1 or 3
2
2 or 3
1
The logic is controlling the correct sequence in closing the switches and in interpreting the 32µs de-bounced HW_Cmp output
accordingly. The output of this small state-machine is corresponding to:
- High or address = 1
- Low or address = 0
- Floating
AMI Semiconductor – Apr. 2007, Rev 3.1, M-20664-003
20
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