Atmega328PB (Pololu A* 328PB Micro 5V 16MHz Item #3160, alternativ Wattuino Pro Mini PB 5V/16MHz), MCP2515-Modul schaltbar versorgt über separaten MCP1755T, 2*TEKT5400S, [2*LPT80A].
Die TEKT5400S sind in einem Gehäuse zusammen mit einem Magneten an die Zähler angeheftet.
An SML message is (usually) 404 bytes long and takes 420ms to transmit. There is one message every second per meter. Thus, there is a 580ms gap between end of message and begin of next. However, messages of the different meters may overlap, and whilst we can alternate the receptions we have only one single CAN output channel. Our serial channels have a 64 bytes reception buffer each, filled via the UART interrupt mechanism, so we can be busy 64ms before calling recv() again. A single watt report takes 9 CAN frames and 9ms in total. A full report for a single meter takes 90ms.
Our handling is as follows: Once a full correct frame has been received from one of the meters we lock the reception buffer of this meter and signal the buffer ready for transmission. In the CAN loop we check for ready buffers and accordingly emit the CAN watt report, followed every minute by a CAN full report for this meter. During CAN emission we continue to handle serial line data reception, virtually for the locked meter (if any, this should normally not happen) but into the buffer proper for the other meter, again locking the buffer and marking it ready for transmission once a full correct frame has been received.
An 5V über 100kΩ:
SFH229 | 77W Halogen aus 50cm | 2,7V | 27uA |
SFH229 | Zimmerbeleuchtung indirekt | 13mV | 130nA |
SFH229 | fast dunkel | 0,2mV | 2nA |
„wie“ LPT80A | 77W Halogen aus 50cm | 4,9V | 50uA |
„wie“ LPT80A | Zimmerbeleuchtung indirekt | 1,2V | 12uA |
„wie“ LPT80A | fast dunkel | 4mV | 40nA |
LPT80A | 77W Halogen aus 50cm | 1,0V | 10uA |
LPT80A | Zimmerbeleuchtung indirekt | 11mV | 110nA |
LPT80A | fast dunkel | 0,2mV | 2nA |