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RE: Question about system bus
- To: "eCos" <ecos-discuss at sources dot redhat dot com>,"Jonathan Larmour" <jlarmour at redhat dot com>
- Subject: RE: [ECOS] Question about system bus
- From: "HuangQiang" <jameshq at liverpool dot ac dot uk>
- Date: Wed, 20 Jun 2001 10:06:17 +0100
My assembly code shows:
*EXTIOTEST = 0x55; // write to external IO bank0 and I can get CS from it
- 0xc744 <cyg_user_start+268>: mov r3, #16 ; 0x10
- 0xc748 <cyg_user_start+272>: add r3, r3, #34603008 ; 0x2100000
- 0xc74c <cyg_user_start+276>: mov r2, #85 ; 0x55
- 0xc750 <cyg_user_start+280>: str r2, [r3]
87
88 k = *EXTIOTEST; // read from external IO bank0 and I can't get CS from
it
- 0xc754 <cyg_user_start+284>: mov r3, #16 ; 0x10
- 0xc758 <cyg_user_start+288>: add r3, r3, #34603008 ; 0x2100000
- 0xc75c <cyg_user_start+292>: ldr r2, [r3]
- 0xc760 <cyg_user_start+296>: str r2, [r11, -#16]
while writing to the external IO bank0 I can get CS and while reading I
can't get CS why?
Thank you!
huang
-----Original Message-----
From: jlarmour@garibaldi.jifvik.org
[mailto:jlarmour@garibaldi.jifvik.org]On Behalf Of Jonathan Larmour
Sent: 20 June 2001 03:01
To: HuangQiang
Cc: eCos
Subject: Re: [ECOS] Question about system bus
HuangQiang wrote:
>
> while(1)
> {
> k = *EXTIOTEST;
> } // now no CS signal.
You may want to disassemble this function to be sure the right thing is
happening.
Jifl
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