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under the hood #1: adding a GPRS module to TW231

a few years ago, with the arrival of the new dreifels controller, modern micro controllers employed within offered many benefits:

  • handling complex charging scenarios
  • more and detailed vehicle data
  • overall better vehicle performance
  • …and a few optional hardware extensions to extend overall vehicle usage comfort.

one of these options is a sms module, which – three years ago – i think TW560 was the first one to have officially.

the module (in its current release 1 feature level) can help alleviate problems ev-drivers experience when charging: unauthorized unplugging during charge, missing power from the grid, knowing when exactly the charge has completed … and for the anally retentive under us: query vehicle and charge status at any given time.

since peter from dreifels identified the bug preventing sms’ being sent and told me what to configure whilst i was visiting this week – jc’s module was ready to be built in! i phoned him friday evening and he told me that he wanted the module sooner than later – if saturday morning would work for me? (he will be very happy to have this functionality during his long-distance trip this summer … more on this to follow soon)

jc arrived early saturday morning and after a good coffee and some TWIKE-related chatting we (i) started working.

the rear cover comes off...

the rear cover comes off…

under the rear cover - batteries, DCDC, controller and many, many other cables...

under the rear cover – batteries, DCDC, controller and many, many other cables…

taking off the main support brackets

taking off the main support brackets

first support screws coming off

first support screws coming off

don't take pictures, take the screws!

don’t take pictures, take the screws!

freeing TWIKE controller from cable tangle

freeing TWIKE controller from cable tangle

jc’s TWIKE has much more space back there than TW560. but nevertheless, it is fairly difficult to get the controller out without disturbing all the other cabling.

opening the controller

opening the controller

free at last!

free at last!

controller pcb close-up with grey rs232 cable connected to microcontroller piggyback pcb

controller pcb close-up with grey rs232 cable connected to microcontroller piggyback pcb

since this is only release 1-functionality (more to follow soon) the controller interfaces with the modem only via at-commands and to the outside world via sms.

before we clean up the cables, let's test if the module works!

before we clean up the cables, let’s test if the module works!

we call TW231’s mobile number … and … keep our fingers crossed and watch TW231’s display.

success, the controller sees the outside world!

success, the controller sees the outside world!

lo and behold, just a few seconds later, we receive a sms!

TW231:
Reichweite 62km, 39%, 379V,
0km/h
Ladezeit 0:00h
Umgebung 13 C

TW231 is indeed not moving and all vehicle data is correct – hurray!

all set. clean setup, ready for the rear cover to go in.

all set. clean setup, ready for the rear cover to go in.

we go back in for another coffee whilst TW231 charges for jc to return home.

sure enough, after some time, we get an sms:

TW231:
Reichweite 160km (99%, 424V)
Ladezeit 0:45h
Umgebung 14 C
Ladung abgeschlossen – Batterie voll.

another saturday morning well spent!