MCF5307, pull down resistor on D0 fail

angelo_d — Thu, 05 Nov 2009 04:04:03 GMT

Dear Gentlemen,

i need some help with the D0 line pulldown, to configure the boot bus clock to half of the processor clock.

I used a 4,7K to pull down to ground, but the level at startup is floating from 2,5 to 1,5V.

On the data bus i have now conected only the MCF5307 and a sdram 48LC4M32B2.

Many thanks,

angelo

Message Edited by spectrum on 2009-11-04 08:04 PM

Re: MCF5307, pull down resistor on D0 fail

angelo_d — Sun, 08 Nov 2009 09:25:39 GMT

hi all,

i read something about,

first. the MCF5307 datasheet says:

See Section 17.5.5, “Data/Configuration Pins (D[7:0]).” Motorola recommends that the
data pins be driven rather than using a weak pull-up or pull-down resistor. Table 17-1 lists
the encoding of these pins sampled at reset.

Is there any diagram on how drive the signals up/down properly ?

then, i have seen that all the signals that control the SDRAM are driven high at reset time from the CPU, but strangely, the SDRAM don't switch the data lines to high impedance.

I am trying to contact micron for support someway.

thanks

Message Edited by spectrum on 2009-11-08 01:26 AM

topic MCF5307, pull down resistor on D0 fail in ColdFire/68K Microcontrollers and Processors

MCF5307, pull down resistor on D0 fail

Re: MCF5307, pull down resistor on D0 fail