ZENTRUM MIKROELEKTRONIK DRESDEN AG
“ASI for you” IC
Datasheet
3.13 Main State Machine
The State Machine controls the overall behavior of the IC. Depending on the configuration data stored in the
E²PROM, the State Machine activates one of the different IC operational modes and controls the digital I/O
ports accordingly. In Slave Mode it processes the received master telegrams and computes the contents of the
slave answer, if required. Table 6 on page 15 lists all master calls that are decoded by the ASI4U in Slave
Mode.
To prevent the critical situation in which the IC gets locked in a not allowed state (i.e. by imission of strong elec-
tromagnetic radiation) and thereby could jeopardize the entire system, all prohibited states of the state machine
will lead to an unconditioned logic reset which is comparable to the AS-i call ”Reset Slave (RES)”.
3.14 Communication Monitor/Watchdog
The IC contains an independent Communication Monitor that observes the processing of Data_Exchange and
Write_Parameter requests. If no such requests have been processed for more than 40.960ms (+5%) the Com-
munication Monitor recognizes a No Data/Parameter Exchange status and turns the red status LED (LED1) on.
Any following Data_Exchange or Write_Parameter request will let the Communication Monitor start over and
turn the red status LED off.
The Communication Monitor is only activated at slave addresses unequal to zero (0) and while the IC is proc-
essing the first Write_Parameter request after initialization. It becomes deactivated at any IC Reset or after the
reception of a Delete_Address Request.
If the Watchdog_Active flag (E²PROM Firmware Area) is set or the P0_Watchdog_Activation flag is set and
Parameter Port P0 is logic high, the Communication Monitor is switched to the so-called Watchdog Mode.
If the Communication Monitor detects a No Data/Parameter Exchange status in active Watchdog Mode, it im-
mediately invokes an unconditioned IC Reset, switching all Data and Parameter Outputs inactive, generating
corresponding Data and Parameter Strobe signals, setting the Data_Exchange_Disable flag and starting the IC
initialization procedure.
In order to resume to normal Data Port communication after a Watchdog IC Reset, the master has to send a
Write_Parameter request again before Data Port communication can be reestablished. This ensures new pa-
rameter setup of possibly connected external circuitry.
3.15 Toggle watchdog for 4I/4O processing in Extended Address Mode
As described in chapter 3.7.5 on page 34 a special 4I/4O data processing is supported in Extended Address
Mode. The transmission of a 4 bit wide output word is achieved by alternation of a high and a low nibble in con-
secutive transactions. To ensure that both output nibbles become refreshed continuously by the Master, the
alternation of the I2 bit in the Data_Exchange call can be supervised by an I2 toggle watchdog in the IC.
The Toggle Watchdog is enabled at slave addresses unequal to zero (0) and while the IC is processing the first
data output event after initialization. It becomes disabled at any IC Reset or after the reception of a De-
lete_Address request.
The Toggle Watchdog function becomes activated only if the IC is operated in 4I/4O Mode (ID_code = 0xA,
Ext_Addr_4I/4O_Mode = ‘1’) and if either the Watchdog_Active flag is set in the E²PROM or the
P0_Watchdog_Activation flag (also E²PROM) is set and Parameter Port P0 is logic HIGH.
If there is no alternation of bit I2 for 327ms (+16ms) at any time after the enable event, an activated Toggle
Watchdog invokes an unconditioned IC Reset, switching all Data and Parameter Outputs inactive, generating
corresponding Data and Parameter Strobe signals, setting the Data_Exchange_Disable flag and starting the IC
initialization procedure. Thus, the reaction of the IC is the same as for an expired Communication Watchdog.
3.16 Write Protection of ID_Code_Extension_1
The ID_Code_Extension_1 register can either be manufacturer configurable or user configurable.
•
If the flag ID_Code1_Protect is set (‘1’) in the firmware area of the E²PROM, ID_Code_Extension1 is
manufacturer configurable.
In this case the slave response to a Read_ID_Code_1 request is constructed out of the data stored in
the Protected_ID_Code_Extension1 register in Firmware Area of the E²PROM.
It doesn’t matter which data is stored in the ID_Code_Extension1 register in the User Area. The IC will
always respond with the protected manufacturer programmed value.
Copyright © 2006, ZMD AG, Rev.1.4
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 preliminary and subject to changes without notice.
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ZMD [ Zentrum Mikroelektronik Dresden AG ]
