The timer0 RTC is reasonably accurate, and can save lots of hardware. Longtime back I had tried using the watch crystal, but good accuracy can be obtained only if the PCB is done well taking care of the capacitance.
Sunish On Sun, Mar 7, 2010 at 7:07 PM, m...@watty <[email protected]> wrote: > > > On Mar 7, 12:34 pm, Sunish Issac <[email protected]> wrote: > > Are using the jallib RTC the one with Roman Black Algorithm ? > > > > Sunish > > Would that be good? > > I'm porting RDS software from a Java demo my son did. I'll > "oversample" the RDS clock pin to read the RDS data pin value at 4kHz, > i.e. a HW 250 us realtime interrupt. > > I was planning on figuring how to use the 32.768KHz crystal and 3V > battery to power PIC only in Sleep and maintain a clock / calendar. > Then on WakeUp, (provoked by external USB power or External power from > Radio ACC/CAT connector), switch to timekeeping via the 250us "tick" > interrupt? > > Since I already have I2C for the 24LC512 and an PCF8593 (I2C RTC) out > of an old VCR, the Plan B is use the PCF8593. It would add expense to > a Production version though. > > I now have all the Radio "Commands" for the FT817 Radio (other Radios > are similar) which has no keypad entry (no keypad). This will allow > sending DTMF tones during transmit and entry of frequency directly > rather than spinning knob or clicking band switch. Full remote > control, microphone, speaker and extra features such as graphical scan > of SWR or signal on a Band. The general purpose Graph plotting and > Signal/Progress bars in JAL will be useful to others. > > I might implement Alarm Clock, Schedule Events such as transmit beacon > or switch Receive to a frequency etc... > Insides of Box in the photos. > http://www.techtir.ie/forums/showpost.php?p=4076&postcount=10 > (thread of features) > > When all working I will do PCB version and order PCBs. The PCB will > fit in cheap handheld case and have: > Mini B USB > 8 way connector with TTL serial, audio in (inc RDS/Stereo) /out, > analog 0 to 4.5V measure in, Power 8V to 16V in > Stereo 3.5mm Audio jack > Aux TTL level I/O connector using PS/2 style MiniDIN (TTL GPS, IR > remote TX, IR Remote RX, Remote Aerial Tuner, etc.. but not all at > once. 4 pins match +5V, OV, Data, clock of PC keyboard pin-out). > 20 way connector for GLCD to allow cable, thus different pinouts of > 128 x64 panel and even Colour panel when cheaper.. > 6 pin Connector for rotary encoder (mechanical or optical with push > switch) > MCLR/5V/OV/RB7/RB6 etc Programming header > connector for 16 to 25 way keypad and 5 way navikey/enter switch. > > Optional HW on PCB: > NE567/LM567 tone Decoder PLL feed PIC (one pin) > TDA7330 RDS decoder feed PIC (two pins) > TDA7040 Stereo Decoder > Stereo Amp feed headphones or mono loudspeaker in case in Bridge mode. > Fed by PIC PWM, and Audio in header and Stereo Decoder > Option CD7088 / TDA7088 type single Chip FM radio receiver. PIC able > to control. > 24LC512 EEPROM > Possibly PCF8593 if can't be avoided. > Coin cell for RTC during Sleep or OFF. (either PIC or PCF8593) > > Space in case for NiMH or LiPoly battery. > > Possibly a custom Keypad PCB using Tact switches rather than 4x4 > keypad + tact switches. > > Apart from my CatPad application, I think this would be generally > useful for handheld projects > > > -- > You received this message because you are subscribed to the Google Groups > "jallib" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]<jallib%[email protected]> > . > For more options, visit this group at > http://groups.google.com/group/jallib?hl=en. > > -- You received this message because you are subscribed to the Google Groups "jallib" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/jallib?hl=en.
