meyers, Author at MitchTech

Home Posts by meyers

MongoDB vs. Postgres; A specific use case

Posted by meyers on Aug 2, 2015 in Tutorials | 3 comments

I’ve recently taken a job at Ansible working on the enterprise offering Tower. In case you don’t know, Tower is a front-end for your Ansible playbooks w/ enterprise permission management. I was tasked with evaluating our database needs for a new System Tracking feature that we released. Working remotely at the time forced me to create detailed presentations on my progress and evaluation. I ended up taking the internal presentations and created a blog post about the evaluation process.

http://www.ansible.com/blog/how-we-chose-mongodb-for-ansible-tower-system-tracking-feature

Devstack on EC2 via Ansible

Posted by meyers on Feb 12, 2015 in Tutorials | 1 comment

131

So you want to get an instance of OpenStack running to poke around and see what all the fuss is about without going insane. Welcome to Devstack. Once Devstack is setup you will have access to a web-based control panel with prepopulated data and instances. You will also be able to explore the OpenStack API with v2.0 and v3 authentication (keystone).

devstack webpanel

Setup

git clone https://github.com/chrismeyersfsu/playbook-devstack
cd playbook-devstack/
sudo ansible-galaxy install -r requirements.yml

Create an ec2 elastic ip address and override the playbook variable ec2_elastic_ip.
Map a domain/subdomain in route53 (or other dns service) to your elasic ip address. (i.e. devstack.example.com)
Set your webportal login password by overriding the playbook variable nova_password

Execution

Be aware that the playbook may take > 20 minutes on an ec2 instance to complete.

ansible-playbook site.yml -i ‘devstack.example.com,’

When finished you should be able to visit http://devstack.example.com and login using demo / nova_password. You should then see the webpanel similar to the image above. The v2.0 and v3 APIs are accessabile via http://devstack.example.com:5000/v2.0/ and http://devstack.example.com:5000/v3/.

Debugging

So things maybe didn’t go according to plan. Here are some playbook invocation variations that you can be used to execute a subset of the tasks.

Do not provision a new ec2 instance. Only run the devstack install task.

ansible-playbook site.yml -i ‘devstack.testing.ansible.com,` -vvvv –tags “devstack_setup”

Do not provision a new ec2 instance nor run the devstack install task. Only run the vm instance creation tasks.

ansible-playbook site.yml -i ‘devstack.testing.ansible.com,` -vvvv –tags “devstack_nova”

Beaglebone + Ubuntu

Posted by meyers on Jun 30, 2013 in Beaglebone, Tutorials | 4 comments

353

We can install Ubuntu 2-ways.

To the external SDCARD
To the internal MMC

Installing to the internal MMC requires an SDCARD to install, but the sdcard is not required after that. The process is mostly the same. The MMC setup vs. the SDCARD setup depends on which image you download.

Installing Ubuntu

MMC: Download the latest file of the form BBB-eMMC-flasher-ubuntu-xx.xx-xxxx-xx-xx.img.xz
SDCARD: Download the latest file of the form ubuntu-12.10-console-armhf-xxxx-xx-xx.tar.xz

Extract the image

sudo apt-get install xz
xz -d *.img.xz

Insert the sdcard into your desktop and note the device path. In my case the device is at /dev/sdc.

meyers@mcbeefy:~/beaglebone$ dmesg
[ 1659.900631] usb 3-1: USB disconnect, device number 3
[ 2664.433700] usb 3-1: new high-speed USB device number 4 using xhci_hcd
[ 2664.709199] scsi7 : usb-storage 3-1:1.0
[ 2665.706903] scsi 7:0:0:0: Direct-Access Generic- SD/MMC 1.00 PQ: 0 ANSI: 0 CCS
[ 2665.707747] sd 7:0:0:0: Attached scsi generic sg3 type 0
[ 2666.334388] sd 7:0:0:0: [sdc] 15519744 512-byte logical blocks: (7.94 GB/7.40 GiB)
[ 2666.334770] sd 7:0:0:0: [sdc] Write Protect is off
[ 2666.334775] sd 7:0:0:0: [sdc] Mode Sense: 03 00 00 00
[ 2666.335066] sd 7:0:0:0: [sdc] No Caching mode page present
[ 2666.335071] sd 7:0:0:0: [sdc] Assuming drive cache: write through
[ 2666.336660] sd 7:0:0:0: [sdc] No Caching mode page present
[ 2666.336667] sd 7:0:0:0: [sdc] Assuming drive cache: write through
[ 2666.337339] sdc: sdc1 sdc2
[ 2666.338721] sd 7:0:0:0: [sdc] No Caching mode page present
[ 2666.338726] sd 7:0:0:0: [sdc] Assuming drive cache: write through
[ 2666.338730] sd 7:0:0:0: [sdc] Attached SCSI removable disk
[ 2666.821868] EXT4-fs (sdc2): mounted filesystem with ordered data mode. Opts: (null)

Flash the image to the sdcard. Substitute <mmc_or_sdcard>.img and /dev/sdX accordingly.

sudo dd if=<mmc_or_sdcard>.img of=/dev/sdX bs=1M

Upon completion remove the sdcard and perform the following:

Ensure the beaglebone is off
If you plan on powering the beaglebone with usb, ensure the ethernet is unplugged.
Insert the sdcard into the beaglebone
Hold down the button that is by itself near the SDCARD
Insert the USB power or barrel jack power
Once the lights begin blinking blue you may release the button
Wait =~ 45 minutes until all the lights are blue

Once all the lights turn solid blue the MMC is successfully flashed and you may power down your beaglebone (unplug the power), remove the sdcard. Wait a couple seconds, then plug the power back in and the system will boot Ubuntu.

Verifying Ubuntu Install

Find the ip of your beaglebone on your network.

meyers@mcbeefy:~$ sudo nmap -sP 192.168.1.*
Starting Nmap 5.21 ( http://nmap.org ) at 2013-06-30 14:13 EDT
Nmap scan report for 192.168.1.1
Host is up (0.00086s latency).
MAC Address: 00:23:69:0E:20:D7 (Cisco-Linksys)
Nmap scan report for 192.168.1.2
Host is up (0.076s latency).
MAC Address: BC:AE:C5:C4:F6:AB (Unknown)
Nmap scan report for 192.168.1.103
Host is up (0.065s latency).
MAC Address: BC:AE:C5:C4:F6:AB (Unknown)
Nmap scan report for 192.168.1.106
Host is up (0.00023s latency).
MAC Address: 3C:07:71:24:21:4B (Unknown)
Nmap scan report for 192.168.1.107
Host is up.
Nmap scan report for 192.168.1.112
Host is up (0.075s latency).
MAC Address: BC:AE:C5:C4:F6:AB (Unknown)
Nmap scan report for 192.168.1.114
Host is up (0.062s latency).
MAC Address: BC:AE:C5:C4:F6:AB (Unknown)
Nmap scan report for 192.168.1.116
Host is up (0.00072s latency).
MAC Address: C8:A0:30:B2:8E:5D (Unknown)
Nmap scan report for 192.168.1.118
Host is up (0.017s latency).
MAC Address: BC:AE:C5:C4:F6:AB (Unknown)
Nmap done: 256 IP addresses (9 hosts up) scanned in 6.18 seconds

ssh to your beaglebone.

ssh [email protected]
[email protected]’s password: temppwd

Raspberry Pi + MSP430 + SPI

Posted by meyers on Aug 13, 2012 in MSP430 Launchpad, Raspberry Pi, Tutorials | 12 comments

113

This tutorial will explain how to communicate from the Raspberry Pi to an MSP430 Launchpad board (M430G2553 chip) using SPI.

Requirements

1 Raspberry pi (running Raspbian)
1 MSP430 TI Launchpad
3 wires

Your raspberry pi should be running the newest version of Raspbian. To ensure your system is up-to-date please download and run rpi-update.

Wiring

MSP430

Flash the below code to your MSP430 chip. Please see this tutorial for information on compiling and programming your MSP430.

MSP430 Code

//****************************************************************************** // MSP430G2xx3 Demo - USCI_A0, SPI 3-Wire Slave Data Echo // // Description: SPI slave talks to SPI master using 3-wire mode. Data received // from master is echoed back. USCI RX ISR is used to handle communication, // CPU normally in LPM4. Prior to initial data exchange, master pulses // slaves RST for complete reset. // ACLK = n/a, MCLK = SMCLK = DCO ~1.2MHz // // Use with SPI Master Incremented Data code example. If the slave is in // debug mode, the reset signal from the master will conflict with slave's // JTAG; to work around, use IAR's "Release JTAG on Go" on slave device. If // breakpoints are set in slave RX ISR, master must stopped also to avoid // overrunning slave RXBUF. // // MSP430G2xx3 // ----------------- // /|\| XIN|- // | | | // | | XOUT|- // Master---+-|RST | // | P1.2|<- Data Out (UCA0SOMI) // | | // | P1.1|-> Data In (UCA0SIMO) // | | // | P1.4|<- Serial Clock In (UCA0CLK) // // D. Dang // Texas Instruments Inc. // February 2011 // Built with CCS Version 4.2.0 and IAR Embedded Workbench Version: 5.10 //****************************************************************************** #include "msp430g2553.h" #include <string.h> char cmdbuf[20]; char cmd_index=0; /** Delay function. **/ void delay(unsigned int d) { int i; for (i = 0; i<d; i++) { nop(); } } void flash_spi_detected(void) { int i=0; P1OUT = 0; for (i=0; i < 6; ++i) { P1OUT = ~P1OUT; delay(0x4fff); delay(0x4fff); } } void main(void) { WDTCTL = WDTPW + WDTHOLD; // Stop watchdog timer /* led */ //P1DIR |= BIT0 + BIT5; P1DIR |= BIT0; while (P1IN & BIT4); // If clock sig from mstr stays low, // it is not yet in SPI mode flash_spi_detected(); // Blink 3 times P1SEL = BIT1 + BIT2 + BIT4; P1SEL2 = BIT1 + BIT2 + BIT4; UCA0CTL1 = UCSWRST; // **Put state machine in reset** UCA0CTL0 |= UCMSB + UCSYNC; // 3-pin, 8-bit SPI master UCA0CTL1 &= ~UCSWRST; // **Initialize USCI state machine** IE2 |= UCA0RXIE; // Enable USCI0 RX interrupt __bis_SR_register(LPM4_bits + GIE); // Enter LPM4, enable interrupts } __attribute__((interrupt(USCIAB0RX_VECTOR))) void USCI0RX_ISR (void) { /* if (UCA0STAT & UCOE) { P1OUT |= BIT0; } */ char value = UCA0RXBUF; if (value == '\n') { if (strncmp(cmdbuf, "HELLO WORLD", 11) == 0) { P1OUT |= BIT0; } else { P1OUT &= ~BIT0; } cmd_index = 0; } else { cmdbuf[cmd_index] = value; cmd_index++; } }

Raspberry Pi

With your updated rasbian system you should have the drivers that you need. Now it’s time to load them.

modprobe spi_bcm2708
modprobe spidev

Check to be sure the modules loaded:

lsmod
Module Size Used by
spidev 5944 0
spi_bcm2708 5350 0
snd_bcm2835 21681 0
snd_pcm 81170 1 snd_bcm2835
snd_seq 59528 0
snd_timer 21602 2 snd_seq,snd_pcm
snd_seq_device 6924 1 snd_seq
snd 57427 5 snd_seq_device,snd_timer,snd_seq,snd_pcm,snd_bcm2835
snd_page_alloc 5343 1 snd_pcm
i2c_bcm2708 3822 0

Raspberry Pi Code

Save the below code as spidev_test.c on to your Raspberry Pi and compile it

gcc spidev_test.c -o spidev_test

/* * SPI testing utility (using spidev driver) * * Copyright (c) 2007 MontaVista Software, Inc. * Copyright (c) 2007 Anton Vorontsov <avorontsov@ru.mvista.com> * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License. * * Cross-compile with cross-gcc -I/path/to/cross-kernel/include */ #include <stdint.h> #include <unistd.h> #include <stdio.h> #include <stdlib.h> #include <getopt.h> #include <fcntl.h> #include <sys/ioctl.h> #include <linux/types.h> #include <linux/spi/spidev.h> #define ARRAY_SIZE(a) (sizeof(a) / sizeof((a)[0])) static void pabort(const char *s) { perror(s); abort(); } static const char *device = "/dev/spidev0.0"; static uint8_t mode; static uint8_t bits = 8; static uint32_t speed = 500000; static uint16_t delay; static void transfer(int fd) { int ret; uint8_t tx[] = { 0x48, 0x45, 0x4C, 0x4C, 0x4F, 0x20, 0x57, 0x4F, 0x52, 0x4C, 0x44, 0x0A }; uint8_t rx[ARRAY_SIZE(tx)] = {0, }; struct spi_ioc_transfer tr = { .tx_buf = (unsigned long)tx, .rx_buf = (unsigned long)rx, .len = ARRAY_SIZE(tx), .delay_usecs = delay, .speed_hz = speed, .bits_per_word = bits, }; ret = ioctl(fd, SPI_IOC_MESSAGE(1), &tr); if (ret < 1) pabort("can't send spi message"); /* for (ret = 0; ret < ARRAY_SIZE(tx); ret++) { if (!(ret % 6)) puts(""); printf("%.2X ", rx[ret]); } puts(""); */ } static void print_usage(const char *prog) { printf("Usage: %s [-DsbdlHOLC3]\n", prog); puts(" -D --device device to use (default /dev/spidev1.1)\n" " -s --speed max speed (Hz)\n" " -d --delay delay (usec)\n" " -b --bpw bits per word \n" " -l --loop loopback\n" " -H --cpha clock phase\n" " -O --cpol clock polarity\n" " -L --lsb least significant bit first\n" " -C --cs-high chip select active high\n" " -3 --3wire SI/SO signals shared\n"); exit(1); } static void parse_opts(int argc, char *argv[]) { while (1) { static const struct option lopts[] = { { "device", 1, 0, 'D' }, { "speed", 1, 0, 's' }, { "delay", 1, 0, 'd' }, { "bpw", 1, 0, 'b' }, { "loop", 0, 0, 'l' }, { "cpha", 0, 0, 'H' }, { "cpol", 0, 0, 'O' }, { "lsb", 0, 0, 'L' }, { "cs-high", 0, 0, 'C' }, { "3wire", 0, 0, '3' }, { "no-cs", 0, 0, 'N' }, { "ready", 0, 0, 'R' }, { NULL, 0, 0, 0 }, }; int c; c = getopt_long(argc, argv, "D:s:d:b:lHOLC3NR", lopts, NULL); if (c == -1) break; switch (c) { case 'D': device = optarg; break; case 's': speed = atoi(optarg); break; case 'd': delay = atoi(optarg); break; case 'b': bits = atoi(optarg); break; case 'l': mode |= SPI_LOOP; break; case 'H': mode |= SPI_CPHA; break; case 'O': mode |= SPI_CPOL; break; case 'L': mode |= SPI_LSB_FIRST; break; case 'C': mode |= SPI_CS_HIGH; break; case '3': mode |= SPI_3WIRE; break; case 'N': mode |= SPI_NO_CS; break; case 'R': mode |= SPI_READY; break; default: print_usage(argv[0]); break; } } } int main(int argc, char *argv[]) { int ret = 0; int fd; parse_opts(argc, argv); fd = open(device, O_RDWR); if (fd < 0) pabort("can't open device"); /* * spi mode */ ret = ioctl(fd, SPI_IOC_WR_MODE, &mode); if (ret == -1) pabort("can't set spi mode"); ret = ioctl(fd, SPI_IOC_RD_MODE, &mode); if (ret == -1) pabort("can't get spi mode"); /* * bits per word */ ret = ioctl(fd, SPI_IOC_WR_BITS_PER_WORD, &bits); if (ret == -1) pabort("can't set bits per word"); ret = ioctl(fd, SPI_IOC_RD_BITS_PER_WORD, &bits); if (ret == -1) pabort("can't get bits per word"); /* * max speed hz */ ret = ioctl(fd, SPI_IOC_WR_MAX_SPEED_HZ, &speed); if (ret == -1) pabort("can't set max speed hz"); ret = ioctl(fd, SPI_IOC_RD_MAX_SPEED_HZ, &speed); if (ret == -1) pabort("can't get max speed hz"); printf("spi mode: %d\n", mode); printf("bits per word: %d\n", bits); printf("max speed: %d Hz (%d KHz)\n", speed, speed/1000); transfer(fd); close(fd); return ret; }

Running

The MSP430 board LED1 will blink 3 times upon recognition of the SPI clock. After this initial sequence, when you SPI data “HELLO WORLD\n” to the MSP430 it will turn on the LED1 light.
On your Raspberry Pi run the previously compiled program. The -s options sets the frequency of the clock when performing the SPI communication.

sudo ./spidev_test -s 120000

Again, a successful sending of “HELLO WORLD\n” will be denoted by LED1 lighting up on the MSP430 board.

Raspberry Pi + Arduino + SPI

Posted by meyers on Aug 11, 2012 in Arduino, Raspberry Pi, Tutorials | 48 comments

297

This tutorial will show you how to communicate from your raspberry pi to your arduino using 3-wire SPI.

Requirements

1 Raspberry pi (running Raspbian)
1 Arduino
4 wires

Your raspberry pi should be running the newest version of Raspbian. To ensure your system is up-to-date please download and run rpi-update.

Wiring

Arduino

Open your Arduino ide and flash the below code to your Arduino.

Arduino code

// Written by Nick Gammon // February 2011 /** * Send arbitrary number of bits at whatever clock rate (tested at 500 KHZ and 500 HZ). * This script will capture the SPI bytes, when a '\n' is recieved it will then output * the captured byte stream via the serial. */ #include <SPI.h> char buf [100]; volatile byte pos; volatile boolean process_it; void setup (void) { Serial.begin (115200); // debugging // have to send on master in, *slave out* pinMode(MISO, OUTPUT); // turn on SPI in slave mode SPCR |= _BV(SPE); // get ready for an interrupt pos = 0; // buffer empty process_it = false; // now turn on interrupts SPI.attachInterrupt(); } // end of setup // SPI interrupt routine ISR (SPI_STC_vect) { byte c = SPDR; // grab byte from SPI Data Register // add to buffer if room if (pos < sizeof buf) { buf [pos++] = c; // example: newline means time to process buffer if (c == '\n') process_it = true; } // end of room available } // end of interrupt routine SPI_STC_vect // main loop - wait for flag set in interrupt routine void loop (void) { if (process_it) { buf [pos] = 0; Serial.println (buf); pos = 0; process_it = false; } // end of flag set } // end of loop

Raspberry Pi

With your updated rasbian system you should have the drivers that you need. Now it’s time to load them.

modprobe spi_bcm2708
modprobe spidev

Check to be sure the modules loaded:

lsmod
Module Size Used by
spidev 5944 0
spi_bcm2708 5350 0
snd_bcm2835 21681 0
snd_pcm 81170 1 snd_bcm2835
snd_seq 59528 0
snd_timer 21602 2 snd_seq,snd_pcm
snd_seq_device 6924 1 snd_seq
snd 57427 5 snd_seq_device,snd_timer,snd_seq,snd_pcm,snd_bcm2835
snd_page_alloc 5343 1 snd_pcm
i2c_bcm2708 3822 0

Raspberry Pi Code

Save the below code as spidev_test.c on to your Raspberry Pi and compile it

gcc spidev_test.c -o spidev_test

Running

Plug your Arduino to your desktop via the serial cable. Open the arduino Serial Monitor and set the bitrate to 115200. Now, on the Raspberry Pi, run the compiled code

sudo ./spidev_test

You should see HELLO WORLD print in the Arduino IDE Serial Monitor.

Debugging

Make sure that your kernel has the required drivers (spi-bcm2708.ko and spidev.ko)

pi@raspberrypi ~/spi $ ls -al /lib/modules/`uname -r`/kernel/drivers/spi/
total 64
drwxrwxr-x 2 pi pi 4096 Aug 10 10:53 .
drwxrwxr-x 23 pi pi 4096 Aug 10 10:53 ..
-rw-rw-r– 1 pi pi 14428 Aug 10 10:53 spi-bcm2708.ko
-rw-rw-r– 1 pi pi 10852 Aug 10 10:53 spi-bitbang.ko
-rw-rw-r– 1 pi pi 15803 Aug 10 10:53 spidev.ko
-rw-rw-r– 1 pi pi 10693 Aug 10 10:53 spi-gpio.ko

Thanks to Nick Gammon for the SPI slave code.

Thanks to Anton Vorontsov for the kernel Documentation spidev_test.c example code.

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