SPI - Revision history

JulienB: /* Linux user space C code */

2018-01-31T14:40:33Z

‎Linux user space C code

2018-01-31T11:06:16Z

2017-08-24T16:57:26Z

‎Tested SPI chips

2017-08-24T16:56:10Z

‎Linux user space C code

2017-08-24T16:54:07Z

‎Usage

2017-08-24T16:52:42Z

‎APF27Dev with 3.19+ kernels

2017-08-07T13:29:12Z

‎APF27Dev with 2.6.29 kernel

2017-08-04T16:12:35Z

‎Linux user space C code

2017-08-04T16:00:41Z

‎APF27Dev with 2.6.29 kernel

2017-08-04T15:59:08Z

‎APF27Dev with 3.19+ kernels

@@ Line 89: / Line 89: @@
   or
 $ cp ./buildroot/output/build/linux-4.x.x/tools/spi/spidev_test.c .    (on recent kernels)
-$ ../buildroot/output/host/usr/bin/arm-linux-gcc -o spidev_test spidev_test.c
+$ ../buildroot/output/host/usr/bin/arm-linux-xxx-gcc -o spidev_test spidev_test.c
 $ scp spidev_test root@192.168.1.22:/root/
 </pre>

@@ Line 5: / Line 5: @@
 [http://en.wikipedia.org/wiki/Serial_Peripheral_Interface_Bus SPI] ('''S'''erial '''P'''eripheral '''I'''nterface) is a 4-wire full-duplex serial bus.
-Wires used in SPI are :
+Wires used in SPI are:
 * '''MOSI''', '''M'''aster '''O'''utput '''S'''lave '''I'''nput : send data to slave.
 * '''MISO''', '''M'''aster '''I'''nput '''S'''lave '''O'''utput : receive data from slave.
@@ Line 11: / Line 11: @@
 * '''SSx''', '''S'''lave '''S'''elect : used to select the slave for communication with master.
-On APF27, the i.MX27 contains 3 SPI devices that can be configured in master (slave is not supported by linux). APF9328 (i.MXL) contains 2 SPI.
+On [[APF27]], the i.MX27 contains 3 SPI devices that can be configured in master (slave mode is not supported by Linux). [[APF9328]] (i.MXL) contains 2 SPI.
 == Linux configuration ==
@@ Line 31: / Line 31: @@
 </pre>
-And user SPI device interface (spidev) option must be selected too (here as a module) :
+And user SPI device interface (spidev) option must be selected too (here as a module):
 <pre class="config">
@@ Line 87: / Line 87: @@
 $ cd spitest
 $ cp ../buildroot/output/build/linux-x.x.x/Documentation/spi/spidev_test.c .
 $ ../buildroot/output/host/usr/bin/arm-linux-gcc -o spidev_test spidev_test.c
 $ scp spidev_test root@192.168.1.22:/root/

@@ Line 100: / Line 100: @@
 * ADC : [[ADC max1027 | Max1027]]
 * EEPROM : [[93LCXX]]
 == Links ==

@@ Line 94: / Line 94: @@
 </pre>
-A simple library named [[AsDevices#SPI | as_spi]] has also been written for Armadeus Project.
+A module named [[AsDevices#SPI | as_spi]] has also been written in AsDevices to ease spidev usage from userspace.
 == Tested SPI chips ==

@@ Line 72: / Line 72: @@
 ==Usage==
-When loaded this driver will create a ''/dev/spidev2.0'' node to read/write on SPI bus from userspace.
+When loaded, this driver will create a ''/dev/spidevN.0'' node to read/write on SPI bus from userspace (N depends on your platform).
 <pre class="apf">
 # modprobe spidev
 </pre>

@@ Line 63: / Line 63: @@
 ===APF27Dev with 3.19+ kernels===
-* SPI3 bus, available on J8 connector, has been configured for spidev. ''/dev/spidev2.0'' is the device to use with these kernels. You'll need an up-to-date ''apf27.dtb''
+* SPI3 bus (CS0), available on J8 connector, has been configured for spidev. ''/dev/spidev2.0'' is the device to use with these kernels. You'll need an up-to-date ''apf27.dtb''
-* To change it you will have to edit ''arch/arm/boot/dts/imx27-apf27dev.dts'' in Linux sources and then recompile kernel (make linux) and update dtb from U-Boot (run update_dtb).
+* to change it you will have to edit ''arch/arm/boot/dts/imx27-apf27dev.dts'' in Linux sources and then recompile kernel (make linux) and update dtb from U-Boot (run update_dtb).
 For more details on spidev usage, see [http://www.mjmwired.net/kernel/Documentation/spi kernel documentation].

@@ Line 42: / Line 42: @@
 </pre>
-With 2.6.29 kernels, on [[APF27Dev]], ''spidev device'' uses the bus number 2 and PortB17 as chip select. So ''/dev/spidev1.2'' has to be used to access your device from userspace. To change this (for expert), the structure ''spi_board_info'' must be modified in platform file apf27-dev.c (in directory ''buildroot/output/build/linux-2.6.29.6/arch/arm/mach-mx2/'') :
+With 2.6.29 kernels, on [[APF27Dev]], ''spidev device'' uses the bus number 2 and PortB17 as chip select (J22 connector, muxed with USB signals). So ''/dev/spidev1.2'' has to be used to access your device from userspace. To change this (for expert), the structure ''spi_board_info'' must be modified in platform file apf27-dev.c (in directory ''buildroot/output/build/linux-2.6.29.6/arch/arm/mach-mx2/'') :
 <source lang="C">