DATA SHEET
HAL856
5. Programming of the Sensor
mand have to be sent to the sensor. After the recog-
nition of the erase and program commands, the
HAL856 answers with an acknowledge pulse on its
output signal. After the acknowledge pulse, a pulse
on the VDD-line is created to start the charging of
the EEPROM cells. Then, the supply voltage is kept
constant during the charging time. To stop the
charging, a further command is sent to the HAL856.
This stopping command can be a further program-
ming command or a read command (see Fig. 5–4
on page 37).
5.1. Definition of Programming Telegram
The sensor is addressed by modulating a serial tele-
gram on the supply voltage. The sensor answers with
a serial telegram on the output pin.
The bits in the serial telegram have a different bit time
for the VDD-line and the sensors answer. The bit time
for the VDD-line is defined through the length of the
Sync Bit at the beginning of each telegram. The bit
time for the sensors answer is defined through the
Acknowledge Bit.
– Lock a sensor
To lock the EEPROM registers, the lock bit has to be
programmed. Write the lock bit into the lock register.
If the telegram is valid and the command has been
processed, the sensor answers with an Acknowl-
edge Bit (logical 0) on the output. In order to store
the lock bit permanently, an erase and program
command have to be sent to the sensor. The same
procedure as mentioned above (Programming the
EEPROM cells Fig. 5–4 on page 37) is used. The
EEPROM registers are locked after a power on
reset.
A logical “0” is coded as no output level change within
the bit time. A logical “1” is coded as an output level
change between 50% and 80% of the bit time. After
each bit, an output level change occurs.
5.2. Definition of the Telegram
Each telegram starts with the Sync Bit (logical 0), 3
bits for the Command (COM), the Command Parity Bit
(CP), 4 bits for the Address (ADR), and the Address
Parity Bit (AP).
Note: It is mandatory to lock the sensor before per-
forming any kind of reliability tests or after the
last programming of the sensor. The HAL856
has its full performance only after setting the
LOCK bit.
There are 4 kinds of telegrams:
– Write a register (see Fig. 5–2 on page 36)
After the AP Bit, follow 14 Data Bits (DAT) and the
Data Parity Bit (DP). If the telegram is valid and the
command has been processed, the sensor answers
with an Acknowledge Bit (logical 0) on the output.
t
t
f
r
high-level
logical 0
t
t
p0
p0
Note: The sensor can only be programmed with pro-
grammer board version 5.1. If you have an older
version, please contact Micronas or your sup-
plier.
or
low-level
t
p1
high-level
– Read a register (see Fig. 5–3 on page 36)
After evaluating this command, the sensor answers
with the Acknowledge Bit, 14 Data Bits, and the
Data Parity Bit on the output.
t
t
p0
p0
logical 1
low-level
or
t
p1
– Programming the EEPROM cells
Fig. 5–1: Definition of logical 0 and 1 bit
In order to permanently store the written data into
the EEPROM cells, an erase and program com-
Micronas
March 23, 2010; DSH000142_002EN
35