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---+ <nop>CAN Bus interface for PANDA

This is the wiki of the PANDA !CAN bus interface for the Raspberry Pi Computer

%TOC%

---++ Requirements

Many devices used in the PANDA Detector Control are controlled via a !CAN bus interface.
Therefore we need also a !CAN bus interface for the front-end computers which can be used with EPICS.
This interface must fulfill the following requirements:
   * High data throughput
   * Availability of hardware
   * Easy maintainability of software
   * Reliability
   * Costs should be as low as possible
   * Little space required
   * Shielding
   * Galvanic insulation

---++ Hardware

A small !PCB using the !SJA1000 stand-alone !CAN controller was developed. This chip has a parallel interface
using eight multiplexed data-/address lines and five control lines. To safe space and keep the costs as low as
possible this chip is directly connected to the general purpose I/O ports of an !CPU.

The developed !PCB has the same dimensions as the [[http://www.raspberrypi.org/][Raspberry Pi Computer]] and
is designed as an extension board for this computer. It also provides a RS232 interface.

    <a href="%ATTACHURLPATH%/rasPI_CAN_front.jpg"><img src="/foswiki/pub/DCS/CAN/rasPI_CAN_front_small.png" alt="rasPi Can front small"  width="250" height="160"  /></a>
    <a href="%ATTACHURLPATH%/rasPI_CAN_front-2.jpg"><img src="/foswiki/pub/DCS/CAN/rasPI_CAN_front-2_small.jpg" alt="rasPi Can front 2 small"  width="265" height="160"  /></a>
    <a href="%ATTACHURLPATH%/rasPI_CAN_back.jpg"><img src="/foswiki/pub/DCS/CAN/rasPI_CAN_back_small.png" alt="rasPi Can back small"  width="250" height="160"  /></a>
---
---+++ Schematics and Layout
   * [[%ATTACHURL%/PANDA-RPi_CAN.pdf][PANDA-RPi_CAN.pdf]]: Schematic of the adapter PCB
   * [[%ATTACHURL%/PANDA-RPi_CAN_brd.pdf][PANDA-RPi_CAN_brd.pdf]]: Board Layout<hr />

---++ Software

The kernel module for the !CAN bus interface is based on the open-source kernel module for
the interfaces by [[http://www.peak-system.com/][PEAK Systems]].

The interface supports all standard bit rates. For testing the performance frames with 8 byte length have been send over the CAN bus:
|  *Bitrate*  |  *Extended*  |  *Standard*  |
|  *kbit/s*  |  *frames/s*  ||
|  5  |  34  |  41  |
|  10  |  69  |  82  |
|  20  |  139  |  165  |
|  50  |  350  |  416  |
|  100  |  689  |  800  |
|  125  |  869  |  1052  |
|  250  |  1666  |  2000  |
|  500  |  3333  |  4000  |
|  1000  |  6666  |  6666  |
All currently supported devices use standard frames @ 125 kbit/s

---+++ EPICS support

EPICS device support for the !CAN bus interface itself and several devices controlled via !CAN bus
is available:
   * ISEG EHS/EDS high voltage power supply
   * Wiener VME crate remote control
   * [[EMC.THMP][THMP]]
   * [[EMC.Lightpulser][Light pulser]]
   * TMCM142 high-performance single axis stepper motor controller/driver
Please refer to [[DCS.SupportedHardware]] for further details on these devices

The source code for the EPICS support and Kernel module can be found on
[[https://github.com/ffeldbauer/epics_RPi_can][github]]

---++ SD-Card Image for Raspberry Pi Computer

A SD-Card image for the Raspberry Pi computer with the kernel module for this interface and EPICS already installed
is available under
[[http://www.ep1.rub.de/~florian/epics/raspi_panda.img.gz][http://www.ep1.rub.de/~florian/epics/raspi_panda.img.gz]]
A 4 GB card is required.

Currently there are two users available:<br />
pi (passwd: raspberry)<br />
 panda (passwd: pandadcs)

An EPICS IOC is installed via the PANDA DCS apt repository. Configuration of the IOC can be done in the dir "/etc/epics/iocpandadcscan/"

After booting the Pi !ProcServ will be started with the EPICS !IOC for CAN bus as child process allowing access via telnet on port 20000.
The child process is not started automatically.

---++ Contact Person

For further questions and suggestions please contact
Main.FlorianFeldbauer

-- Main.PeterZumbruch - 26 Jun 2013<br />
-- Main.FlorianFeldbauer - 02 Feb 2015

Topic attachments
I	Attachment	Action	Size	Date	Who	Comment
pdf	PANDA-RPi_CAN.pdf	manage	67.3 K	26 Jun 2013 - 10:38	FlorianFeldbauer	Schematic of the adapter PCB
pdf	PANDA-RPi_CAN_brd.pdf	manage	160.5 K	28 Jun 2013 - 07:28	FlorianFeldbauer	Board Layout
jpg	rasPI_CAN_back.jpg	manage	1867.9 K	26 Jun 2013 - 12:57	PeterZumbruch	rasPi Can back
png	rasPI_CAN_back_small.png	manage	275.8 K	26 Jun 2013 - 12:57	PeterZumbruch	rasPi Can back small
jpg	rasPI_CAN_front-2.jpg	manage	1473.5 K	26 Jun 2013 - 12:58	PeterZumbruch	rasPi Can front 2
jpg	rasPI_CAN_front-2_small.jpg	manage	98.8 K	26 Jun 2013 - 12:58	PeterZumbruch	rasPi Can front 2 small
jpg	rasPI_CAN_front.jpg	manage	1738.8 K	26 Jun 2013 - 12:59	PeterZumbruch	rasPi Can front
png	rasPI_CAN_front_small.png	manage	275.6 K	26 Jun 2013 - 12:58	PeterZumbruch	rasPi Can front small

Topic revision: r9 - 03 Feb 2015, PeterZumbruch

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