Linux CAN drivers development
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From: Oliver Hartkopp <socketcan@hartkopp.net>
To: Yasushi SHOJI <yasushi.shoji@gmail.com>
Cc: "Marc Kleine-Budde" <mkl@pengutronix.de>,
	"Remigiusz Kołłątaj" <remigiusz.kollataj@mobica.com>,
	"Yasushi SHOJI" <yashi@spacecubics.com>,
	"Wolfgang Grandegger" <wg@grandegger.com>,
	linux-can@vger.kernel.org
Subject: Re: [PATCH] can: mcba_usb: Fix termination command argument
Date: Thu, 24 Nov 2022 21:15:21 +0100	[thread overview]
Message-ID: <70b9e4a0-69ed-ba6a-ac3a-4e20aa9fc251@hartkopp.net> (raw)
In-Reply-To: <CAELBRWKz57boSG1B=ONQ1Ax2TXw9FTHj36aG6p0VKp_tyHx2mg@mail.gmail.com>

Hi Yashi,

On 24.11.22 14:13, Yasushi SHOJI wrote:

> I've checked with one of my colleagues and he told me I measured it wrong.

Ok.

> Here is a correction.
> 
> You can find the schematic of the analyzer in its user's guide
> https://www.microchip.com/en-us/development-tool/APGDT002
> or directly at https://ww1.microchip.com/downloads/aemDocuments/documents/APG/ProductDocuments/UserGuides/CAN-Bus-Analyzer-Users-Guide-DS50001848C.pdf
> 
> The schematics is at page 11.
> 
> Basically the "termination" controls the CAN_RES signal.  When it's
> low, R24 and R25 are connected to the bus.
> They are 56 Ohms.

Ah, that means 2 x 56 Ohms => 112 Ohms (nearly 120)

> With my patch, "termination 120" drives CAN_RES low and the resistors
> are active, and "termination 0" drives it high.

Thanks for the clarification!

Best regards,
Oliver

  reply	other threads:[~2022-11-24 20:15 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-11-23 19:44 [PATCH] can: mcba_usb: Fix termination command argument Yasushi SHOJI
2022-11-23 22:34 ` Marc Kleine-Budde
2022-11-24  9:50   ` Yasushi SHOJI
2022-11-24 10:09     ` Oliver Hartkopp
2022-11-24 12:32       ` Yasushi SHOJI
2022-11-24 13:13       ` Yasushi SHOJI
2022-11-24 20:15         ` Oliver Hartkopp [this message]
2022-11-24  0:53 ` Vincent Mailhol
2022-11-24  9:52   ` Yasushi SHOJI
2022-11-24  9:54     ` Vincent Mailhol
2022-11-24 14:38     ` Marc Kleine-Budde

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