On Mar 12, 7:06 am, vasile surducan <[email protected]> wrote: > On Fri, Mar 12, 2010 at 7:56 AM, mattschinkel <[email protected]>wrote: > > > > Matt, RTCC it's already in the PIC. It needs only the 32768 connected at > > > T1OSI/T1OSO. > > > Why writing clock-calendar when is already implemented with hardware > > > registers? > > > Of course it works with TMR1 as well. > > > Any reasonable 32768 TCXO or crystal I found in the neighbourhood is > > 5ppm, > > > no less so be it. > > > Because not all PIC's have hardware RTCC and becuase you will only > > need 1 oscillator. It's just preference, so it's up to you.
If the PIC has the 32.768kHz osc option with HW counter while asleep, then this seems cheapest option. I'm trying it soon. I just need to have my PIC auto sleep/wait and make sure coin cell only supplies the PIC. The PCF8593 (wouter sells them €5) is best option for RTC/Cal if it is not possible on PIC. But if you NEED a cheap RTC solution then choose a PIC that supports it and design it in. Many under €6 ? An oscillator on its own is no use if the PIC has no HW counting while in Sleep Mode. A TCXO / VCTCXO or oven or GPS based RTC is no use on a backup battery. They take too much power. A second PIC with 32.768kHz support and implement I2C slave can be maybe cheaper than a PCF8593 and perhaps also be your Power Manager for rest of board with main PIC. I have designed on the 32.768KHz on my CatPad. I will try make it work in Sleep with Coin Cell. Current major problem is RF interference on the Radio from the TTL serial connection. I will do PCB of Catpad which will give people a good Prototyping general project PCB for a handheld 128x64 GLCD PIC18F4550 project. Either this box ZB16S HH2 http://maplin.co.uk/Module.aspx?moduleno=1686 or this box N21GC RH3165 http://maplin.co.uk/Module.aspx?ModuleNo=224581 Unless someone has a better idea? With the ZB16S HH2 I had to cut off the edges of the 128x64 GLCD PCB. :-( There will be two PCBs. One for 4x4 buttons, 4 menu, 4way+centre button navi switch and rotary encoder and a bicolour LED and GLCD connector and the other with all the CPU and other ICs, I/O connectors, on board coin cell. I may have a LiPoly PSU (2 to 4.5V single cell or dual cell) with charger, under voltage etc and +5V and other voltages via SMPSU on main PCB too with option to use 4 x AAA or 2 x AA NiMH also. Lithium coin cell on PCB for RTC. -- 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.
