hey guys,
i'm really impressed (and envious) of your range with the 69HW's. i've been wrestling with the RFM69.cpp for what seems like weeks now trying to find a combination that works, but i'm afraid my lack of experience is what's hobbling me. I've looked at all the posts regarding lowering bitrates on this forum, but i may be missing something (or a lot of things) but let me run this past you and tell me if i'm missing something obivous-
in looking at the previous post by hdphillip, he lists
bitrate 1200
RegFdev 2000
RegRxBw 0x19,0x56
so, if i want to drop the bitrate to 1200, i'll need to change this block in the rfm69.cpp
/* 0x03 */ { REG_BITRATEMSB, RF_BITRATEMSB_55555}, //default:4.8 KBPS
/* 0x04 */ { REG_BITRATELSB, RF_BITRATELSB_55555},
/* 0x05 */ { REG_FDEVMSB, RF_FDEVMSB_50000}, //default:5khz, (FDEV + BitRate/2 <= 500Khz)
/* 0x06 */ { REG_FDEVLSB, RF_FDEVLSB_50000},
to reflect these changes:
/* 0x03 */ { REG_BITRATEMSB, RF_BITRATEMSB_1200}, //default:4.8 KBPS
/* 0x04 */ { REG_BITRATELSB, RF_BITRATELSB_1200},
/* 0x05 */ { REG_FDEVMSB, RF_FDEVMSB_2000}, //default:5khz, (FDEV + BitRate/2 <= 500Khz)
/* 0x06 */ { REG_FDEVLSB, RF_FDEVLSB_2000},
though it appears I’ll also need to adjust this line as well
/* 0x19 */ { REG_RXBW, RF_RXBW_DCCFREQ_010 | RF_RXBW_MANT_16 | RF_RXBW_EXP_2 }, //(BitRate < 2 * RxBw)
but it lists 0x56, and I’m not quite sure what to make of that- I’ve searched for this combination through all of the files and can’t quite make sense of what I should do with that.
I’ve tried to read as much as I can on this topic before posting, and I see in the comments in the forums and that the bitrate/freqdev and bwrx are interrelated. I’ve also read that it’s possible to comment out the init functions that call to the non default values and return the 69hw to it’s orig. settings, which sounds like a great way to learn which settings need to be changed in order to affect the bitrate. I looked for an init function that calls to the sepcs listed above, but haven’t been able to find it (if someone can point me in the right direction there as well, I’d be very grateful)
Also, My technological acumen isn’t quite sharp enough to parse the hope rfm69 pdf so hopefully someone might be able to explain the best way to drop the bitrate in order to achieve the longer distance that I need for my project. The data I’m sending is quite minimal so and I’d like to ideally have a large spread of nodes per gateway. I’ve had great luck so far but this is my weakest part of the process, so I’m really hoping that I’ll be able to achieve some better transmission distances with the lower bitrates.
Thanks so much and I really look forward to your suggestions and replies. If there is any more information I can give you to help better answer my questions, I’ll be happy to.