APPLICATION NOTE HAL8xy, HAL100x
Programmer Board
Micronas Sept. 19, 2013; APN000046_03EN 67
6.3. Programming of the Sensor
6.3.1. Definition of Programming Pulses
The sensor is addressed by modulating a serial telegram 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 output.
The bit time for the VDD-line is defined through the length of the Sync bit at the begin-
ning of each telegram. The bit time for the output is defined through the Acknowledge
bit.
A logical “0” is coded as no voltage change within the bit time. A logical “1” is coded as
a voltage change between 50% and 80% of the bit time. After each bit, a voltage
change occurs.
6.3.2. 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).
There are 4 kinds of telegrams:
Write a register Write a register
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 (see Fig. 6–2).
Read a register After evaluating this command, the sensor answers with the Acknowledge bit, 14 Data
bits, and the Data Parity bit on the output (see Fig. 6–3).
Programming the
EEPROM cells
In order to permanently store the written data into the EEPROM cells, an erase and
program command have to be sent to the sensor. After the recognition of the erase and
program commands, the HAL855 answers with an acknowledge pulse on its output sig-
nal. After the acknowledge pulse, a pulse on the VDD-line is created to start the charg-
ing 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 HAL855. This stopping
command can be a further programming command or a read command (see Fig. 6–5).
Activate a sensor If more than one sensor is connected to the supply line, selection can be done by first
deactivating all sensors. With an Activate pulse on the appropriate output pin, an indi-
vidual sensor can be selected. All following commands will only be accepted from the
activated sensor (see Fig. 6–4).
Lock a sensor To lock the EEPROM registers, the lock bit has to be programmed. Write the lock bit
into the lock register (see Fig. 6–2). If the telegram is valid and the command has been
processed, the sensor answers with an Acknowledge 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. This is the same procedure as mentioned above (see Programming
the EEPROM cells and Fig. 6–5). The EEPROM registers are locked after a power on
reset.