ASI4U_12 Datasheet, PDF (37/64 Pages) List of Unclassifed Manufacturers – 3.0 Compliant Universal AS-I IC

ASI4U / ASI4U-E / ASI4U-F
Spec. 3.0 Compliant Universal AS-I IC
The filter time can be adjusted jointly for all input channels in seven steps by programming the
DI_Filter_Time_Constant register in the Firmware Area of the E²PROM. The following coding table applies:
Table 19: Data Input Filter Time Constants
DI_Filter_Time_Constant, Tolerance = - 6.25%
0
1
2
3
4
Corresponding input 128 256 512
filter time constant ^µs
µs
µs
1024
µs
2048
µs
5
4096
µs
6
8192
µs
7
AS-i
cycle
If AS-i cycle mode is selected, a new input value is returned to the master if equal input data was sampled for
two consecutive Data_Exchange cycles. As long as the condition is not true, previous valid data is returned.
To suppress undesired input data validation in case of immediately repeated Data_Exchange calls (i. e. AS-i
Masters immediately repeat one Data_Exchange requests if no valid slave response was received on the first
request) input data sampling is blocked for 256µs (-6.25%) after every sampling event in AS-i cycle mode.
DEXCHG Addr 1
Slave DEXCHG Addr1
Slave
DEXCHG Addr 1
Slave
Input
Signal
This sampling event is
blocked to avoid immediate
input data validation.
Filter
Output
< 256 µs (-6.25%)
Sampling Point
> 256 µs (-6.25%)
Figure 13: Principle of AS-i cycle input filtering (exemplary for Slave with Address 1)
The DI_Filter_Configuration register provides channel selective enabling of input filters; just as the
DI_Invert_Configuration register allows individual inverting of the four Data Port input channels. Again, the
index of the DI channel corresponds to the bit position within the register. Thus, data at input channel DI0 is
filtered if Bit 0 of the DI_Filter_Configuration register is set and consequently input channel DI3 is filtered if Bit
3 is set.
In general the Data Input Filters become active, as the corresponding bit in the DI_Filter_Configuration
Register is set.

They are initialized with ‘0’ and the filter timer is reset after the initialization phase of the IC. (The
first is because an AS-i Master interprets data inputs at ‘0’ to be inactive.)

If the P1_Filter_Activation flag is set to ‘1’, the filters will also start to run after the initialization phase,
however the data to construct the slave response is either taken from the actual Data Input values or the
filtered values, depending on the state of Parameter Port P1
Table 20: Input Filter Activation by Parameter Port Pin P1
P1_Filter_Activation Flag
0
1
1
Parameter P1
Don’t care
1
0
Data Input Filter Function
ON, active filters depend on DI_Filter_Configuration
OFF
ON, active filters depend on DI_Filter_Configuration
Data Sheet
April 2, 2012
© 2012 Zentrum Mikroelektronik Dresden AG — Rev. 2.2
All rights reserved. The material contained herein may not be reproduced, adapted, merged, translated, stored, or used without
the prior written consent of the copyright owner. The information furnished in this publication is subject to changes without notice.
37 of 63