How to make a backup of DVRPTR-NET bootable microSD This article illustrates how to make a backup of your DVRPTR-NET bootable microSD using an Ubuntu Linux PC. Unfortunately I didn't find an easy way to do a copy using Windows because DVRPTR-NET uses an ext filesystems unsupported by Windows. In this case you could use a virtual machine using SunVirtual Box. microSD to microSD copy Insert the master microSD in your Linux PC. Three new folders will appear on your desktop: ? ? ? kernel rootfs data Remove the target microSD and insert it again. Three new folders will appear on your desktop: ? ? ? kernel_ rootfs_ data_ Open a terminal session on your PC and type: $ $ $ $ $ $ $ sudo sudo sudo sync sudo sudo sudo cp -rp /media/kernel/. /media/kernel_/. cp -rp /media/rootfs/. /media/rootfs_/. cp -rp /media/data/. /media/data_/. umount /media/kernel_ umount /media/rootfs_ umount /media/data_ microSD to tar file copy This method is useful if you want to have a snapshot of your microSD contents on your hard disk to use as master to create new copy. DG1HT Insert the master microSD in your Linux PC. Three new folders will appear on your desktop: ? ? ? kernel rootfs data Open a terminal session and type: $ cd /media/kernel $ sudo tar -cvjSf ../kernel.tar.bz2 . ... $ cd /media/rootfs $ sudo tar -cvjSf ../rootfs.tar.bz2 . ... $ cd /media/data $ sudo tar -cvjSf ../data.tar.bz2 . ... The options mean: ? ? ? ? ? -c create a new archive -v verbosely list files processed -j filter the archive through bzip2 -S handle sparse files efficiently -f use archive file or device ARCHIVE On the /media directory will appear the new three tarbal files: ? ? ? kernel.tar.bz2 rootfs.tar.bz2 data.tar.bz2 usable as master for the microSD clone. tar file to microSD copy Partition and format a new microSD following the instruction on this article: Be sure that the three new partitions are mounted and visible: $ ls -al /media total 170120 drwxr-xr-x 5 root drwxr-xr-x 22 root drwxr-xr-x 3 root -rw-r--r-- 1 root drwx------ 2 root -rw-r--r-- 1 root drwxr-xr-x 21 root -rw-r--r-- 1 root root root root root root root root root 4096 4096 4096 137 16384 1797040 4096 172364479 2011 -08-16 2011 -08-16 2011 -07-13 2011 -08-16 1970 -01-01 2011 -08-16 2010 -09-22 2011 -08-16 12:23 09:12 18:08 12:23 01:00 12:05 16:17 12:09 . .. data data.tar.bz2 kernel kernel.tar.b z2 rootfs rootfs.tar.bz2 Be sure that kernel, rootfs and data are directory and not files. Type: DG1HT $ cd /media $ sudo tar -xvjpSf kernel.tar.bz2 -C /media/kernel ... $ sudo tar -xvjpSf rootfs.tar.bz2 -C /media/rootfs ... $ sudo tar -xvjpSf data.tar.bz2 -C /media/data ... $ sync $ sudo umount /media/kernel $ sudo umount /media/rootfs $ sudo umount /media/data MicroSD partitioning The bootable microSD currently provided by Acme with Debian preinstalled is organized in 4 partitions: Format Label Size type Mount point 1 FAT16 kernel 32MB /media/mmc_p1 2 EXT4 3 EXT4 4 SWAP rootfs 800MB / data 800MB /media/data swap 128MB Description Linux Kernel image and some optional file used by the bootloader at startup Linux root filesystem User data Available for memory swap Brand new microSDs tipically are formatted with a unique big FAT partition so the operation to do are: ? ? ? Delete the factory default big FAT partition Create the four partition requested by the DVRPTR-NET Copy the file inside the new partitions Let's see how to do using an Ubuntu Linux PC. We have to use a Linuc PC because unfortunately on Windows PC it is impossible to manage the Linux filesystems ext4 e swap using the standard tools. Insert the microSD memory card in your Linux PC through a card adapter and start a terminal session. Type: $ dmesg ... [13736.699438] GB/1.86 GiB) [13736.700061] [13736.700067] [13736.700072] [13736.702662] [13736.702671] [13736.709301] [13736.709309] $ sd 15:0:0:0: [sdb] 3911680 512 -byte logical blocks: (2.00 sd 15:0:0:0: sd 15:0:0:0: sd 15:0:0:0: sd 15:0:0:0: sdb: sdb1 sd 15:0:0:0: sd 15:0:0:0: [sdb] [sdb] [sdb] [sdb] Write Protect is off Mode Sense: 4b 00 00 08 Assuming drive cache: write through As suming drive cache: write through [sdb] Assuming drive cache: write through [sdb] Attached SCSI removable disk DG1HT This indicates that the unique FAT16 partition of microSD is allocated as /dev/sdb1 disk and mounted on /media/. It is very important to well understand which is the device allocated for the microSD (in this case /dev/sdb ) to avoid to erase your main hard disk !! Install GParted GParted is a graphical utility to create partition on any memory support like hard-disk, pen drive and SD cards. To install it use Synaptic (System -> Administration -> Synaptic Package Manager) and install gparted. When installed launch it from System -> Administraion -> Gparted menu. Prepare the microSD The following operations will destroy all the data contained on microSD so please be sure that you don't have any useful file on your microSD card. Select /dev/sdb device checking if the size match with the size of your microSD then the /dev/sdb1 partition on it and unmount it using right click -> unmount. Delete it using right click -> delete. DG1HT Create a new partition using the command right click -> New with these parameters: ? ? ? ? New size: 32MB File system: fat16 Label: kernel Leave all the other fields at default values Create a new partition using the command right click -> New with these parameters: ? New size: 800MB or more if you intend to install a lot of Linux packages ? ? ? File system: ext4 Label: rootfs Leave all the other fields at default values DG1HT Create a new partition using the command right click -> New with these parameters: ? ? ? ? File system: ext4 Free space following: 128MB Label: data Leave all the other fields at default values Create a new partition using the command right click - New with these parameters: ? ? ? ? ? New size: 128MB File system: linux-swap Label: swap Leave all the other fields at default values Click on the green sign to apply all the operations and exit from Gparted. DG1HT Remove the microSD, wait about 10 sec and insert again. Tree new partitions will be mounted automatically on: ? ? ? /media/kernel /media/rootfs /media/data Now proceed to fill these partitions with the contents required by the DVRPTR-NET. Kernel uImage and rootfs contents Download the last shapshot from the binary repository then: Copy the Linux Kernel uImage and parameters files in /media/kernel. $ cp uImage /media/kernel $ cp machtype.txt /media/kernel $ cp cmdline.txt /media/kernel Untar and copy the rootfs contens in /media/rootfs: $ sudo tar xvjpSf rootfs.tar.bz2 -C /media/rootfs Syncronize the microSD contents: $ sync Umount all the microSD partition from your PC: $ sudo umount /media/kernel $ sudo umount /media/rootfs $ sudo umount /media/data Remove the microSD, insert it in your DVRPTR-NET and try to boot it. DG1HT How to use the SPI bus The Serial Peripheral Interface Bus or SPI bus is a synchronous serial data link standard that operates in full duplex mode. Devices communicate in master/slave mode where the master device initiates the data frame. Multiple slave devices are allowed with individual slave select (chip select) lines. Sometimes SPI is called a "four-wire" serial bus, contrasting with three-, two-, and one-wire serial buses. Read more on Wikipedia. This article is a just practical guide for how to use the SPI bus on the DVRPTR-NET. To have a more in depth idea of how the SPI works under Linux please read the kernel documentation on: ? ? Kernel documentation of SPI Kernel documentation of spidev The signals required by a SPI bus are distributed on DVRPTR-NET and Daisy-1 connectors in this way: Function DVRPTR-NET pin Daisy-1 pin Signal MOSI Master Output Slave Input J7.10 D7.2 MISO Master Input Slave Output J7.9 D7.3 J7.7 D7.4 SCLK Slave Clock CS0 Chip Select 0 J7.8 D7.5 CS1 Chip Select 1 J7.19 D7.6 CS2 Chip Select 2 N.A. D7.7 CS3 Chip Select 3 J7.27 D7.8 The signals CS0 to CS3 are called in SPI standards - "SS". With 4 SS signals it is possible to wire up to 4 SPI slave devices. Using the SPI from userspace A driver called spidev is provided by the Linux Kernel to manage the SPI bus from user space. This driver is already enabled on the Kernel image provided by Acme on the standard microSD but you have to register each bus line (from 0 to 3 from each CS line) on this file board-dvrptr-net.c. DG1HT These are the lines to add: static struct spi_board_info DVRPTR-NETg20_spi_devices[] = { #if !defined(CONFIG_MMC_AT91) { .modalias = "mtd_dataflash", .chip_select = 1, .max_speed_hz = 15 * 1000 * 1000, .bus_num = 0, }, #endif // First line to add { .modalias = "spidev", .chip_select = 0, .max_speed_hz = 10 * 1000 * 1000, .bus_num = 1, .mode = SPI_MODE_3, }, { .modalias = "spidev", .chip_select = 1, .max_speed_hz = 10 * 1000 * 1000, .bus_num = 1, .mode = SPI_MODE_3, }, { .modalias = "spidev", .chip_select = 2, .max_speed_hz = 10 * 1000 * 1000, .bus_num = 1, .mode = SPI_MODE_3, }, { .modalias = "spidev", .chip_select = 3, .max_speed_hz = 10 * 1000 * 1000, .bus_num = 1, .mode = SPI_MODE_3, }, // Last line to add }; To generate a new kernel image and use it on the DVRPTR-NET read this page: [Tag h1 not found]. The field .mode set the clock signal line polarity and phase. To know more about it read here and here. The following symbols should be added to the Kernel config; using the make ARCH=arm menuconfig you should enable: CONFIG_SPI_SPIDEV=y CONFIG_SPI=y CONFIG_SPI_MASTER=y CONFIG_SPI_ATMEL=y DG1HT After a reboot of the DVRPTR-NET with the new image some new devices will appear on /dev directory: debarm:/# ls crw------- 1 crw------- 1 crw------- 1 crw------- 1 /dev/spi* root root root root root root root root -l 153, 153, 153, 153, 0 1 2 3 Feb Feb Feb Feb 10 10 10 10 10:51 10:51 10:51 10:51 /dev/spidev1.0 /dev/spidev1.1 /dev/spidev1.2 /dev/spidev1.3 Some final consideration As stated before the spi mode is an important parameter that should be trimmed according to your slave device and in accompliance with the modes available here. Now follow some graphs of the spidev behaviours captured with an oscilloscope. In the following images the cyan trace is the SCLK signal, the yellow trace is MOSI signal and at the end the green trace is n-th CS. Spidev on chipselect 0 The trace below was captured using the following kernel definition: { .modalias = "spidev", .chip_select = 0, .max_speed_hz = 1000000, .bus_num = 1, .mode = SPI_MODE_3, }, using the echo spi0 > /dev/spidev1.0 command as spidev writer. Please note that the training char in the captured image is a carrier return introduced by echo. DG1HT Spidev on chipselect 1 The trace below was captured using the following kernel definition: { .modalias = "spidev", .chip_select = 1, .max_speed_hz = 1000000, .bus_num = 1, .mode = SPI_MODE_1, }, using the echo test > /dev/spidev1.1 command as spidev writer. Note that using a mode1 the behaviour of clock signal is different. Spidev on chipselect 2 The trace below was captured using the following kernel definition: { .modalias = "spidev", .chip_select = 2, .max_speed_hz = 1000000, .bus_num = 1, .mode = SPI_MODE_3 | SPI_LSB_FIRST, }, using the echo -n spi2 > /dev/spidev1.2 command as spidev writer. DG1HT Note that in this final capture the mode is the binary OR of more than one flag defined inside spi.h kernel header The captured traces show also that the byte-ordering is inverted due to SPI_LSB_FIRST flag and also that only 4 char are sent on the bus due to the -n option of echo command that supprime the carrier return. Link utili ? ? ? Wikipedia definition of SPI bus Kernel documentation of SPI Kernel documentation of spidev How to use the I2C bus I2C is a multi-master serial single-ended bus invented by Philips that is used to attach lowspeed peripherals to an embedded system. Since the mid 1990s, several competitors (e.g., Siemens AG (later Infineon Technologies AG), NEC, Texas Instruments, STMicroelectronics (formerly SGS-Thomson), Motorola (later Freescale), Intersil, etc.) have brought I2C products onto the market, which are fully compatible with the NXP (formerly Philips's semiconductor division) I2C-system. SMBus, defined by Intel in 1995, is a subset of I2C that defines the protocols more closely. One purpose of SMBus is to promote robustness and interoperability. Accordingly, modern I2C systems incorporate policies and rules from SMBus, sometimes supporting both I2C and SMBus with minimal re-configuration required. (Read more on Wikipedia...). DG1HT This article is a just practical guide for to use the I2C bus on the DVRPTR-NET. To have a more in depth idea of how the I2C works under Linux please read the Linux Kernel documentation on: ? Kernel documentation of I2C Using i2c-tools The faster way to do the first experiments with this board is by installing and using the i2ctools. i2c-tools is a package contains a heterogeneous set of I2C tools for Linux such as: ? ? ? ? ? a bus probing tool a chip dumper a register-level access helpers an EEPROM decoding scripts ...and more To install i2c-tools on the DVRPTR-NET just type: debarm:~# apt-get update debarm:~# apt-get install i2c-tools Using i2cdetect i2cdetect is an userspace program to scan an I2C bus for devices. It outputs a table with the list of detected devices on the specified bus. ? i2cdetect man page Example: debarm:~# 0 1 00: 10: -- -20: 20 -30: -- -40: -- -50: -- -60: -- -70: -- -- i2cdetect -y 0 2 3 4 5 6 -- -- -- --- -- -- -- --- -- -- -- --- -- -- -- --- -- -- -- --- -- -- -- --- -- -- -- --- -- -- -- -- 7 --------- 8 -------- 9 -------- a -------- b -------- c -------- d -------- e -------- f -------- In this case a device has been detected on address 20 hex. Using i2cset i2cset is a small helper program to set registers visible through the I2C bus. ? i2cset man page DG1HT The following simple command writes the byte value 255 to the I2C device at address 20 hex on the i2c bus 0 (/dev/i2c-0). debarm:~# i2cset -y 0 0x20 255 If for example you are using a PCF8574 I2C I/O expander this command will set all the GPIO lines to 1. import smbus import time bus = smbus.SMBus(0) for a in range(0,256): bus.write_byte_data(0x20,0x00, a) time.sleep(0.1) C example The following example sends a sequence of values from 0 to 255 to the PCF8574 I2C I/O expander at address 0x20 in C language. #include #include #include #include <stdio.h> <fcntl.h> <linux/i2c-dev.h> <errno.h> #define I2C_ADDR 0x20 int main (void) { int value; int fd; fd = open("/dev/i2c-0", O_RDWR); if (fd < 0) { printf("Error opening file: %s \n", strerror(errno)); return 1; } if (ioctl(fd, I2C_SLAVE, I2C_ADDR) < 0) { printf("ioctl error: %s\n", strerror(errno)); return 1; } for (value=0; value<=255; value++) { if (write(fd, &value, 1) != 1) { printf("Error writing file: %s \n", strerror(errno)); } usleep(100000); } return 0; } DG1HT Write internal EEPROM #include <avr/eeprom.h> #DG1HT struct settings_t { long time; int analogVal; float temp; char name[50]; } settings; void setup() { Serial.begin(115200); // Set Struct variable settings.time=100000; settings.analogVal=analogRead(0); settings.temp=23.15; strcpy(settings.name,"Test EEPROM"); // Write configuration in EEPROM eeprom_write_block ((const void*)&settings, (void*)0, sizeof(settings)); Serial.println("EEPROM written with this configuration:" ); Serial.print("name: "); Serial.println(settings.name); Serial.print("time: "); Serial.println(settings.time); Serial.print("analogVal: "); Serial.println(settings.analogVal); Serial.print("temp: "); Serial.println(settings.temp); } void loop() { } DG1HT Read internal EEPROM #include <avr/eeprom.h> #DG1HT struct settings_t { long time; int analogVal; float temp; char name[50]; } settings; void setup() { Serial.begin(115200); // Read stored configuration eeprom_read_block ((void*)&settings, (void*)0, sizeof(settings)); Serial.println("Read configuration:" ); Serial.print("name: "); Serial.println(settings.name); Serial.print("time: "); Serial.println(settings.time); Serial.print("analogVal: "); Serial.println(settings.analogVal); Serial.print("temp: "); Serial.println(settings.temp); } void loop() { } Related links ? Wikipedia EEPROM definition DG1HT Debug Port Interface (DPI) DPI is an interface designed to access to the DVRPTR-NET Debug port using a normal USB port of your PC DG1HT DPI is based on the popular FTDI FT232 chip. The relative driver is almost ever already installed on any PC either Window or Linux. If not get it from http://www.ftdi-chip.com. To use the DPI you need a terminal emulator program that is an utility that can send and receive characters via a serial port. Serial terminal emulator on Windows PC By default Windows provide an utility called HyperTerminal that is usable with DPI but we suggest to install a free utility called putty because it can works also as a SSH remote terminal useful to have access to the DVRPTR-NET command prompt via LAN Download putty it from this link. It doesn't need to be installed, just download and run it. At startup you have to specify: ? ? ? Connection type: Serial Serial line: COMx where x is the serial port allocated by the ftdi device driver Speed: 115200 Save this configuration and press the Open button to continue. You will reveice a request of login end password from the DVRPTR-NET G20. Use these credentials: DG1HT Login: root Password: 10011001 DVRPTR-NET:/# Serial terminal emulator on Linux PC A simple terminal emulator available on Linux is minicom. On Ubuntu distribution you can install it using Synaptic or apt-get install by typing: ~$ apt-get install minicom After installation run it by typing: ~$ minicom Type CTRL-A followed by O to show the configuration panel. Then select Serial port setup and access to the serial port configuration. Se the port as shown below: Welcome to minicom 2.4 OPTI+----------------------------------------------------------------------+ Comp| A Serial Device : /dev/ttyUSB0 | Port| B - Lockfile Location : /var/lock | | C Callin Program : | Pres| D - Callout Program : | | E Bps/Par/Bits : 115200 8N1 | | F - Hardware Flow Control : No | | G - Software Flow Control : No | | | | Change which setting? | +----------------------------------------------------------------------+ | Screen and keyboard | | Save setup as dfl | | Save setup as.. | | Exit | +-------------------------- + Type ESC the select Save setup as dfl. Then ESC again. Now pressing Enter you could have access to the DVRPTR-NET login: Login: root Password: 10011001 DVRPTR-NET:/# DG1HT