PurpleTentacle wrote:I am also working on connecting a DCF77 receiver to my monochron. I would prefer not to add an extra microcontroller (ATTiny-idea) to the clock.
nice to hear, I'm not alone! Thanks for your thoughts. Here are mine:
PurpleTentacle wrote:The pins PB4 and PB5 are not free. They are connected to the display.
I do not agree. Take a look at the schematics
. Pin PB4 is MISO, PB5 is SCK. They are only used during reprogramming the chip.
PurpleTentacle wrote:The RXD (PD0) and TXD (PD1) pins can be very useful for sending/receiving debug messages to/from a PC. I would not use them for anything else, if possible.
PurpleTentacle wrote:The Pin PC1 is free and can be used to connect the receiver. It is not an interrupt-pin so you have to poll.
That's a problem - hopefully only in my mind. I have by now no idea how to poll that pin often enough to distinguish a binary 0 to a binary 1. Do you have an idea?
PurpleTentacle wrote:Have you thougt of which timer you want to use? As all three timers are in use, i think i will do the polling in the interrupt function of timer 0, which is called once every millisecond.
No, I havn't, because I never thought about polling that pin. But maybe there is a possibility to do it, I'll be fine with that.
PurpleTentacle wrote:If you still plan to use a second microcontroller, you should pick one with SPI. This makes serial communication to the main microcontroller a lot easier. In my opinion, ISP is also a must-have. Maybe you can use something like an ATTiny48. If you are searching for examples how to evaluate the serial data
on the main microcontroller, you can take a look at the code of the GPS-mod.
My plans so far are to use this
receiver module - I have one already with this
clock and it works fine. There is enough room inside the case to have a controller inside.