Hello,
I work with an controller (with two crystals - 32.768kHz and 18.432MHz). When the controller starts only the 32.768kHz crystal is working - the main crystal is only working if I turn it on by software.
At the moment I've no main crystal - only the 32.768kHz crystal installed; if I download some code to the internal memory I use for the "max. JTAG clock option" 1MHz - what is the relation between this Jtag clock and the crystal from the controller? I've thought, that I'll not be able to store some code within the controller with a higher frequency then the crystal is running...
best regards Scott Alan
Exactly what processor did you said you where using?
I'm using the AT91SAM9260 controller from atmel.
I've another strange problem with the 32.768kHz crystal - it is running at the correct frequency but the AC voltage is only 50mV - which is very small.. the DC voltage is 240mV which should be ok.
the processor is running but it would be very nice to know how I could achieve a higher AC voltage.
By the way the AT91SAM9260 has only ROM (read-only) so I'm not really able to write some code to this internal ROM - but uvision says that I'm able to erase the ROM and programm it -> then I get the error (which is correct) that verify fails...
I download a small code where I'll start the main oscillator which is not connected - but I'm able to see that the voltage at the Xout and Xin for the main crystal is 0V for a short time... so that means the code is running at the internal SRAM.
best regards Alan Scott
Do you have any suggestion to solve the problem with the external crystal (AC voltage)- or do you know why I'm able to download code to the internal RAM with JTAG clock 1MHz (when I only use the 32.768kHz crystal)?
any hint or conclusion would be very helpful.
do you know why I'm able to download code to the internal RAM with JTAG clock 1MHz (when I only use the 32.768kHz crystal)? I do not know the Arghmel chips, but all JTAG chips I know do not use the "CPU clock" for downloading, just TCK.
Erik
thanks for your reply... could you imagine what would be the problem for the low AC voltage at the crystal? The frequency is correkt and I'm able to download some code into the internal RAM, but I never saw such a low AC voltage... the DC voltage for the crystal is 240mV (which should be enough)...
I've tested a few crystals - always the same result.
Does Atmel have any document about how hard they drive the crystal?
I assume that the chip has support for very, very, very low power consumption running with the clock crystal.
could you imagine what would be the problem for the low AC voltage at the crystal? 1) 32 kHz crystals are tricky 2) based on comments on the latest '51s from Arghmel, Arghmel has 'forgotten' how to make good oscillators. 3) Keil forum is really not about oscillators and such, but about the Keil tools, there is a therad in an appropiate forum www.8052.com/.../read.phtml regarding making 32kHz xtals 'sing'.
I spoke with atmel too, but they said that the AC voltage must be higher than 50mV - they could only say that the DC voltage is ok for the 32.768kHz crystal.
I only ask in this forum, because maybe everyone of you has the same error in one of your earlier implementations of atmel chips e.g....