HP 35s (and 42s) Crystal replacement - Printable Version +- HP Forums (https://archived.hpcalc.org/museumforum) +-- Forum: HP Museum Forums (https://archived.hpcalc.org/museumforum/forum-1.html) +--- Forum: Old HP Forum Archives (https://archived.hpcalc.org/museumforum/forum-2.html) +--- Thread: HP 35s (and 42s) Crystal replacement (/thread-130623.html) |
HP 35s (and 42s) Crystal replacement - Lyuka - 01-08-2008 Reacentry I got some cylindrical crystal resonator of 65.536kHz.
Overclocking 42s is successful, however,
Quote: If the frequency of the crystal does not affect the calculation speed, what is the use of the crystal? What is clocking the MPU, I wonder? Re: HP 35s (and 42s) Crystal replacement - DaveJ - 01-08-2008 Quote:
This has been answered in previous threads. The main oscillator frequency can also be software controlled with various divider ratios. So there will be a register in the processor somewhere where you could also change the frequency. Check the Sunplus processor datasheet for details.
Dave.
Re: HP 35s (and 42s) Crystal replacement - Lyuka - 01-08-2008 Quote:
Thanks DaveJ Re: HP 35s (and 42s) Crystal replacement - Nelson M. Sicuro (Brazil) - 01-08-2008 Hi! Best regards,
Nelson
Re: HP 35s (and 42s) Crystal replacement - NACHO - 01-08-2008 then if HP 42S uses or has sam hardware as 17BII then it is possible to upgrade 17BII to 32K?
thanks
Re: HP 35s (and 42s) Crystal replacement - Nelson M. Sicuro (Brazil) - 01-08-2008 Hi, Best regards,
Nelson Edited: 8 Jan 2008, 12:44 p.m.
Re: HP 35s (and 42s) Crystal replacement - Mike Morrow - 01-08-2008 What RTC functions are available on the HP 35s? I've never seen any description of this facility on the HP 35s. But then, there aren't *any* detailed official HP descriptions of HP35S functions available on HP web sites. I wonder why, after all the months that the HP 35s has been out, there is still no manual for the HP 35s available for download.
Mike
Re: HP 35s (and 42s) Crystal replacement - Eric Smith - 01-08-2008 In the 35s, the RTC oscillator is used for display refresh and keyboard scanning.
Re: HP 35s (and 42s) Crystal replacement - Lyuka - 01-08-2008 Thank you.
I've been a bit confused by the word 'RTC'.
Re: HP 35s (and 42s) Crystal replacement - DaveJ - 01-09-2008 Quote: The Sunplus micro does not appear to have a hardware RTCC in it, but the external low power crystal is designed primarily to implement an RTCC in software. But you can also use it for other things as HP have done in this case.
See:
Dave. Edited: 9 Jan 2008, 4:18 a.m.
Re: HP 35s (and 42s) Crystal replacement - Lyuka - 01-09-2008 Thanks DaveJ I've got the data sheet of the GPLB31A and confirmed its block diagram.
Lyuka
Quadruple(x4) speed 42s - Lyuka - 01-11-2008 With setting the speed register at 0x40300 to 0xF by using the built-in debugger,
Power supply current (fclock=65.536kHz, *(0x40300)==0xF, Vbattery=4.71V(SR44~3), Ta=23‹C) |