From mboxrd@z Thu Jan 1 00:00:00 1970 Subject: EP405 GPIO signal problem From: Toni Van Remortel Reply-To: t.vanremortel@ha.be To: Embedded PPC Content-Type: text/plain; charset=ISO-8859-15 Message-Id: <1069336934.1290.6.camel@toni> Mime-Version: 1.0 Date: Thu, 20 Nov 2003 15:02:15 +0100 Sender: owner-linuxppc-embedded@lists.linuxppc.org List-Id: Hi, I have an RTAI powered kernel module which outputs 32 bits data via the EP405 GPIO ports from the IBM 405GP CPU. These outputs are multiplexed with other signals. Problem: when I output the 32 bits as one like this: writel( buffer, (u32)gpio_base_addr+GPIO0_OR ); (where buffer is of u32 type) I get some glitches after my DAC. The DAC has a 70ns settling time, but the glitches are 120µs. So I presume it's a CPU problem. Is this a normal thing? I don't think so. It is strange behavior, that's all I know. How can I prevent those 'peaks' in my output? Peaks are generated by 0xFFFFFFFF output (that's what I can make out of the scope-signal). -- Toni Van Remortel Wetenschappelijk Medewerker - D-science lab Real time Linux for embedded systems: http://linemb.d-sciencelab.com Tel: +32 3 205 61 72 - Fax: +32 3 205 61 95 E-mail: t.vanremortel@ha.be ** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/