Share a thermometer that uses the computer to directly drive the DS1621 temperature measurement through the serial port.

The experimental work discovered today is very classic. It uses the computer to directly drive the DS1621 temperature measurement through the serial port. The whole temperature measurement module is simplified, and no single-chip microcomputer and level conversion chip are used. The technologies involved include serial port power, I2C bus, etc. .

     

If the SLR is used to drive the DS1621, the workload is huge. For example, it is necessary to complete the level conversion and communication between the computer and the single chip; the communication between the MCU and the DS1621 needs to be completed. Alberto Ricci Bitti's PC-implemented thermometer cancels the transfer of the MCU, and the DS1621 is directly driven by the computer, eliminating the need for a large amount of design work in the MCU part. The idea is very sharp, and it is like a magical work. This classic method is only enough to talk directly to the schematic.

Serial port power: The energy consumption of the whole board is not high, and the weak current that is stolen through the serial port is enough to meet the needs of the DS1621. The 12V that the diodes D1 and D2 steal on the DTR and RTS are filtered by C1, and the LM2936-Z5 is stepped down to 5V, which is used as the power supply for the whole system. The input voltage of the LM2936 can be as low as 5.2V, even if some computers have a RS232 high level of only 6V, which is sufficient.
RS232 Analog I2C: Level shifting is required, which is achieved by a 5V Zener. The analog I2C bus uses three wires of RS232. I made a simple table so that it is simpler and clearer.