topic Code Example For Stop2 Mode ? in 8-bit Microcontrollers

Code Example For Stop2 Mode ?

m2s — Thu, 16 Aug 2007 21:56:21 GMT

Hy, I'm wondering if someone have an example on how they save all register value into ram and get them back into the register when returning from Stop2 mode.

Is theyre a faster way than simply copy the information regsiter by regsiter ?

best regards.

Re: Code Example For Stop2 Mode ?

Ake — Mon, 20 Aug 2007 19:37:46 GMT

The fastest way for saving the registers would be something like this

pshh ;save h 2

pshx ;save x 2

psha ;save a 2

tpa ;get a copy of the status register 1

psha; and save it 2

tsx; get stack pointer to hx 2

sthx savedSP ;save the stack pointer 4

So it would take 2+2+2+1+2+2+4 = 15 clock cycles or 0.75 uS on a 20 Mhz 9S08.

In the savedSP word the SP should be saved so when the CPU is powered up, it first checks the savedSP word. If it is < 0xffff, the saved data can be restored. If = 0xffff, no data has been saved.

Regards,

Ake

Re: Code Example For Stop2 Mode ?

m2s — Tue, 21 Aug 2007 18:36:13 GMT

Thank's

To that I need to add the instructions to save all I/O regsiter to.