From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stefan Wahren Subject: Re: i2c-bcm2835: Unable to read from i2c0 Date: Fri, 29 Jan 2016 19:16:35 +0100 Message-ID: <56ABAC83.4000402@lategoodbye.de> References: <7de3fd0b-7973-476c-a009-e9a1fb032a80@email.android.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <7de3fd0b-7973-476c-a009-e9a1fb032a80-2ueSQiBKiTY7tOexoI0I+QC/G2K4zDHf@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-rpi-kernel" Errors-To: linux-rpi-kernel-bounces+glkr-linux-rpi-kernel=m.gmane.org-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org To: Phil Cc: linux-rpi-kernel , linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-i2c@vger.kernel.org Hi Phil, Am 28.01.2016 um 23:49 schrieb Phil: > A few questions: > > 1) What has changed in your system? Have you ever been able to use the PiGlow? please avoid top-posting. I'm using I2C just for a short time, so i don't know if there was a different behavior before. I tested the PiGlow with the following kernel versions: Raspbian Wheezy 3.18 Raspbian Jessie 4.1.13 Mainline 4.5rc-1 All of them show the same detect behavior (see below). Writing to the SN3218 works good, i can enable and disable the LEDs ... But i can't read back any values. I've replaced the PiGlow with a Adafruit Si1145. After that the chip is detected in both cases, but the error messages (i2c transfer failed) still appear. > > 2) What is the state of the GPIOs? What do you mean? configuration of both I2C0 pins? Do you want a register dump? Thanks Stefan > > Phil > > On 28 Jan 2016 9:43 p.m., Stefan Wahren wrote: >> >> Hi, >> >> i'm using a Raspberry Pi B (rev 1) and Linux kernel 4.5rc-1. I have >> connected a PiGlow (SN3218 at address 0x54) to the P1 Header. The I2C >> bus clock is set to 100 kHz. Every time i want to read data from i2c0 >> the following error appear: >> >> [ 94.343612] i2c-bcm2835 20205000.i2c: i2c transfer failed: 100 >> >> According to the BCM2835 datasheet this should be an ERR ACK (Slave has >> not acknowledged its address). >> >>> i2cdetect -y 0 >> 0 1 2 3 4 5 6 7 8 9 a b c d e f >> 00: -- -- -- -- -- -- -- -- -- -- -- -- -- >> 10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- >> 20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- >> 30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- >> 40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- >> 50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- >> 60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- >> 70: -- -- -- -- -- -- -- -- >> >>> i2cdetect -q -y 0 >> 0 1 2 3 4 5 6 7 8 9 a b c d e f >> 00: -- -- -- -- -- -- -- -- -- -- -- -- -- >> 10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- >> 20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- >> 30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- >> 40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- >> 50: -- -- -- -- 54 -- -- -- -- -- -- -- -- -- -- -- >> 60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- >> 70: -- -- -- -- -- -- -- -- >> >> Strangly writing data to the SN3218 works. >> >> Does anyone have an explanation for this error? >> >> Regards >> Stefan >> >> _______________________________________________ >> linux-rpi-kernel mailing list >> linux-rpi-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org >> http://lists.infradead.org/mailman/listinfo/linux-rpi-kernel