Sensorsoft ST6105C, Руководство пользователя

Страница: 22 / 27

Sensorsoft Thermometer User’s Manual
SENSORSOFT DEVICE STATUS BYTE FORMAT
BIT NAME DESCRIPTION
0 Low power supply Voltage is unacceptable for reliable operation
1 IRQ enable N/A
2 IRQ pending N/A
3 Power-up Sensorsoft device just powered-up
4 Tamper Sensor element is disconnected or broken
5 NV option N/A
6 EEPROM fail N/A
7 Future use N/A
A “logic one” condition on any of these bits indicates the condition is set or active. Otherwise,
they are reset to “logic zero”. It’s a good practice for the host to check the status of the Sensorsoft
device regularly in case a bit status changes.
If bit 0 is set, the Sensorsoft device power supply voltage is too low.
If bit 3 is set, the Sensorsoft device has just powered-up. This bit gets reset after the status is read.
If bit 4 is set, the sensor element has become damaged, disconnected, or is being subjected to a
high level of RFI (Radio Frequency Interference) or EMI (Electro Magnetic Interference).
Bits 1,2,5,6 and 7 can be ignored - they are not used.
Converting SSDP DATA-byte(s) to temperature readings
Recent Sensorsoft temperature measuring devices can output temperature readings in two
different formats.
The first format is common to all Sensorsoft temperature measuring devices and is easiest for
programmers to support. It provides a resolution of 0.5 degree Celsius. Commands that query
register or variable
<01h> in the Sensorsoft Thermometer will receive a two byte response in the
DATA-byte(s) placeholder, as described below.
It is the job of the host software to convert the DATA-byte(s) to a floating-point number. It is
then possible to display readings in Celsius or Fahrenheit scale. The following procedure explains
the required steps:
1.
Check the value of the most significant DATA-byte. If it is FFh, the number is negative and
requires processing by steps 2,3,4 and 5. If it is 00h, the number is positive and requires
processing by steps 3 and 5.
2.
Invert the bits of the least significant DATA-byte, then add 1 to it.
3.
Convert the least significant DATA-byte to a floating-point number.
4.
Multiply the previous by -1 to get the negative result.
22