Derouville sylvain

slow pin i/o manipulation

Discussion created by Derouville sylvain on Sep 28, 2008
Latest reply on Sep 29, 2008 by Derouville sylvain
Good morning,
first, sorry for my poor english...
 
I'm starting with the Coldfire V2, I just buy a training card with MCF52223.
I was training with the most common device: I2C, UART ... However, I have a problem with the fast change state of a pin, I explain:
My Quartz is 48 Mhz, the Pll seems set correctly (I have a frequency of 80 MHz output CLKOUT), but the maximum frequency change of state is only 3.63 Mhz, is this normal or due to limitation ?
I watched the assembler code and it seems the simplest:
 
2000070A: 7001 moveq # 1, d0
2000070C: 13C04010000E move.b d0, 0x4010000E (0x4010000e)
20000712: 42394010000E clr.b 0x4010000E (0x4010000e)
20000718: 60F2 bra.s hand 0 xa (0x2000070c); 0x2000070c
 
result of
 
while (1)
{
 PORTTA=0x01;
 PORTTA=0x00;
}
 
thanks.

 


Message Edited by Sly535 on 2008-09-28 09:26 PM

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