Updating TI Beagleboard to 3.x Linux from Angstrom Embedded Distro

I've have one of these neat TI Beagleboard for a couple years, have not used it for a while. TI recently released a new hardware implementation of this family called the Beaglebone. This device looks to be more useable for hardware interfacing, so I picked up a couple to explore. At USD 90, the price of the Beaglebone shows the continued downward price curve of powerful embedded hardware.

I dusted off the older Beagleboard to do some comparisons with the newer Beaglebone hardware. So first off I decided to get the distro version as close as possible. Angstrom appears to be most used and updated distro for the family, but the Android folks look to be getting some steam up.

Here are my notes on getting the most current Angstrom distro running on the Beagleboard.

The one big gotcha that may trip up forever n00b's like me was the change of the TTY port naming conventions. The correct port name for the serial port on the Beagleboard is:

ttyO2

that is a capital OOOOOO as in Oscar not a zero!

After Linux kernel version 2.6.36 the naming convention appears to have moved from:

ttySx

--to--

ttyOx

I'm sure there is a really good reason to slipstream this change in, but not only is it not clearly announced / documented around the various Linux and embedded internet resources [one of those "weed 'em out events perhaps?"] but using the capital 'O' character seems to be making for more opportunities for mistakes by confusing it with the number zero '0'.

The standard instructions to create a SD card with the two partitions containing the u-Boot and linux kernel on the first FAT partition and the remaining core Linux core OS files on the second [one of several types] Linux/Unix formatted partition is straight forward and does not vary from prior configs.

The main two changes to get the console output and the a serial terminal login prompt are as follows:

1) change the Linux bootargs console value to be:

console=ttyO2

REMEMBER THAT IS A CAPITAL O NOT A ZERO!

my basic u-Boot environment variable 'bootargs' is as follows:

bootargs=console=ttyO2,115200n8 root=/dev/mmcblk0p2 rw rootwait

2) Before you put the SD card into the Beagleboard, or after via the X Window session that comes up by default, edit the inittab file in /etc and change the following line from:

S:2345:respawn:/sbin/getty 115200 ttyS2

--to--

S:2345:respawn:/sbin/getty 115200 ttyO2

this will give you a login prompt on the Beagleboard's serial port.

Results and experiences to date.

I am still testing the 3.x kernel on the Beagleboard, so far so good. The serial port might be exhibiting some slow down after a the machine is up for a while. I need to get more data on this. Unfortunately, most of my focus is on the new Beaglebone, so the '..board' is getting the 'old dog' treatment. The puppy is the center of attention.

I updated the two boot modules of the Beagleboard to what I believe is the most current version. You get these by putting the MLO and u-boot.bin files on the FAT boot partition when you download the latest build of Angstrom. There are couple of thinks to be aware of with these upgrades. The version of these files that are in the flash memory of the Beagleboard are the older version until you use the u-boot commands to re-flash them. The instructions to do this are straight forward and worked fine. The 'gotcha' here comes in that the commands in u-boot have changed considerable and the boot scripts are stored as environment variables in the flash. So your old boot scripts will work with with your old SD cards and when you boot these files from flash [by removing the SD card or holding down the 'user' button during power up]. However, when you boot with the newer u-boot, thinks quit working. And, unfortunately, it appears to be even worse than the new versions don't work the same as to older version. It appears that the documentation and perhaps some of the commands do not work as documented that you will find on the 'help' sites on the web. I have not got my arms around these 'additional' issue yet so take this with a grain of salt, but do watch carefully as commands run. One example of what I am talking about is the 'mmc' command family to work with the SD card. There is much discussion of a 'mmcinit' command, but I could not find that command anywhere. What I did find is that before reading from the SD card, it is a good idea to do a 'mmc reset' each time before loading a file or doing a directory of the mmc. Below is my before and simple v1 'after' environments:

-- before version of environment variables that booted a October 2009 Angstrom Linux --

OMAP3 beagleboard.org # printenv

bootcmd=if mmc init; then if run loadbootscript; then run bootscript; else if run loaduimage; then run mmcboot; else run nandboot; fi; fi; else run nandboot; fi
bootdelay=10
baudrate=115200
loadaddr=0x82000000
console=ttyS2,115200n8
vram=12M
dvimode=1024x768MR-16@60
defaultdisplay=dvi
mmcargs=setenv bootargs console=${console} vram=${vram} omapfb.mode=dvi:${dvimode} omapfb.debug=y omapdss.def_disp=${defaultdisplay} root=/dev/mmcblk0p2 rw rootfstype=ext3 rootwait
nandargs=setenv bootargs console=${console} vram=${vram} omapfb.mode=dvi:${dvimode} omapfb.debug=y omapdss.def_disp=${defaultdisplay} root=/dev/mtdblock4 rw rootfstype=jffs2
loadbootscript=fatload mmc 0 ${loadaddr} boot.scr
bootscript=echo Running bootscript from mmc ...; source ${loadaddr}
loaduimage=fatload mmc 0 ${loadaddr} uImage
mmcboot=echo Booting from mmc ...; run mmcargs; bootm ${loadaddr}
nandboot=echo Booting from nand ...; run nandargs; nand read ${loadaddr} 280000 400000; bootm ${loadaddr}
stdin=serial
stdout=serial
stderr=serial
dieid#=1c04000300000000040323090e01600d

Environment size: 1056/131068 bytes
OMAP3 beagleboard.org # 


-- simple 'after' version that boots the Angstrom November 2011 3.x Linux --

OMAP3 beagleboard.org # printenv
baudrate=115200
beaglerev=Cx
bootaddr=0x80300000
bootargs=console=ttyO2,115200n8 root=/dev/mmcblk0p2 rw rootwait
bootcmd=mmc rescan 0; fatload mmc 0 ${loadaddr} uImage; bootm ${bootaddr}
bootdelay=10
buddy=unknown
buddy2=unknown
dieid#=1c04000300000000040323090e01600d
filesize=338778
loadaddr=0x80300000
stderr=serial
stdin=serial
stdout=serial
video=omapfb:2M,vram:4M
vram=12M

Environment size: 412/131068 bytes
OMAP3 beagleboard.org # 


Here is what is running on the Beagleboard now:

Linux beagleboard 3.0.8+ #1 Tue Nov 1 21:14:19 CET 2011 armv7l unknown


Some useful web sites:

Good basic setup instruction of the Beagleboard. Old so it does not address the problems I highlighted above, but still a good anchor to go back to:

http://www.ibm.com/developerworks/linux/library/l-beagle-board/

Beagleboard web site:

http://beagleboard.org/

Angstrom Linux for Beagleboard latest version. NOTE: go to the Amazon AWS mirror of this web site to get much faster download of files:

http://www.angstrom-distribution.org/demo/beagleboard/

Summary...

Pretty frustrating waste of time I had as a n00b here because the 'in the know' folks that are maintaining this stuff did not take five minutes to document some of the rather major changes. Glad I have it working! The Beagleboard and Beaglebone are great training ground for the amazing world of embedded connected inexpensive devices we are moving to. 

Simple learning example for digital to analog on Arduino with MicroChip MC 4921

The Arduino hardware only provides PWM pseudo-DAC support. I had the need to create a simple set of signal wave forms, so I though I would try and accomplish it with the Arduino. I had a AdaFruit Wave Shield v1.1 sitting around, a neat device that does a number of things, but primarily focused on playing back audio files from it's attached SD card reader. I looked around for some code to create wave forms with its on board MicroChip MC 4921 12 bit DAC, but found nothing that was written directly for the Wave Shield. Several folks have posted info on using the MCP 4921 with the Arduino in projects, so I follow their leads and hacked up the code I needed. Below is a simple first step I used to learn to talk to the DAC chip, might give others a starting point. It also shows the basics for storing data in the program code memory of the ATMEL x28 processors. The sine table is far too big to fit in data memory on the Arduino.

Thanks to the folks cited in the comments below for their work.

 

// DAC-programming01
// 30-May-2011
// direct programming of Microchip MCP 4921 12 bit D to A on the AdaFruit WaveShield v1.1 
// Dave Proffer
//
// demonstrates programming the MCP4921 to generate several different wave forms
// look like about 0.666 hertz or 1.5 seconds per cycle on Dumilanove with ATmega328 16 Mhz
// sine wave generated by : http://www.daycounter.com/Calculators/Sine-Generator-Calculator.phtml
// initial MCP 4921 code from: http://www.csulb.edu/~hill/ Prof. G. C. Hill at CSULB
//


#include 

#define DATAOUT     4  //MOSI
#define SPICLOCK    3  //sck
#define SLAVESELECT 2  //ss
#define LDAC 5

#define ledPin       13
 
  word sensorValue;
  word interval;
  byte data = 0;
  
// this sine wave table, 1024 12 bit words is too big for the RAM of the Arduino, so we use the ATMEL rountes to store in in the much larger program non-vol mem
  PROGMEM prog_uint16_t sineLookup[1024] = 
{
2048,2060,2073,2085,2098,2110,2123,2135,2148,2161,
2173,2186,2198,2211,2223,2236,2248,2261,2273,2286,
2298,2311,2323,2335,2348,2360,2373,2385,2398,2410,
2422,2435,2447,2459,2472,2484,2496,2508,2521,2533,
2545,2557,2569,2581,2594,2606,2618,2630,2642,2654,
2666,2678,2690,2702,2714,2725,2737,2749,2761,2773,
2784,2796,2808,2819,2831,2843,2854,2866,2877,2889,
2900,2912,2923,2934,2946,2957,2968,2979,2990,3002,
3013,3024,3035,3046,3057,3068,3078,3089,3100,3111,
3122,3132,3143,3154,3164,3175,3185,3195,3206,3216,
3226,3237,3247,3257,3267,3277,3287,3297,3307,3317,
3327,3337,3346,3356,3366,3375,3385,3394,3404,3413,
3423,3432,3441,3450,3459,3468,3477,3486,3495,3504,
3513,3522,3530,3539,3548,3556,3565,3573,3581,3590,
3598,3606,3614,3622,3630,3638,3646,3654,3662,3669,
3677,3685,3692,3700,3707,3714,3722,3729,3736,3743,
3750,3757,3764,3771,3777,3784,3791,3797,3804,3810,
3816,3823,3829,3835,3841,3847,3853,3859,3865,3871,
3876,3882,3888,3893,3898,3904,3909,3914,3919,3924,
3929,3934,3939,3944,3949,3953,3958,3962,3967,3971,
3975,3980,3984,3988,3992,3996,3999,4003,4007,4010,
4014,4017,4021,4024,4027,4031,4034,4037,4040,4042,
4045,4048,4051,4053,4056,4058,4060,4063,4065,4067,
4069,4071,4073,4075,4076,4078,4080,4081,4083,4084,
4085,4086,4087,4088,4089,4090,4091,4092,4093,4093,
4094,4094,4094,4095,4095,4095,4095,4095,4095,4095,
4094,4094,4094,4093,4093,4092,4091,4090,4089,4088,
4087,4086,4085,4084,4083,4081,4080,4078,4076,4075,
4073,4071,4069,4067,4065,4063,4060,4058,4056,4053,
4051,4048,4045,4042,4040,4037,4034,4031,4027,4024,
4021,4017,4014,4010,4007,4003,3999,3996,3992,3988,
3984,3980,3975,3971,3967,3962,3958,3953,3949,3944,
3939,3934,3929,3924,3919,3914,3909,3904,3898,3893,
3888,3882,3876,3871,3865,3859,3853,3847,3841,3835,
3829,3823,3816,3810,3804,3797,3791,3784,3777,3771,
3764,3757,3750,3743,3736,3729,3722,3714,3707,3700,
3692,3685,3677,3669,3662,3654,3646,3638,3630,3622,
3614,3606,3598,3590,3581,3573,3565,3556,3548,3539,
3530,3522,3513,3504,3495,3486,3477,3468,3459,3450,
3441,3432,3423,3413,3404,3394,3385,3375,3366,3356,
3346,3337,3327,3317,3307,3297,3287,3277,3267,3257,
3247,3237,3226,3216,3206,3195,3185,3175,3164,3154,
3143,3132,3122,3111,3100,3089,3078,3068,3057,3046,
3035,3024,3013,3002,2990,2979,2968,2957,2946,2934,
2923,2912,2900,2889,2877,2866,2854,2843,2831,2819,
2808,2796,2784,2773,2761,2749,2737,2725,2714,2702,
2690,2678,2666,2654,2642,2630,2618,2606,2594,2581,
2569,2557,2545,2533,2521,2508,2496,2484,2472,2459,
2447,2435,2422,2410,2398,2385,2373,2360,2348,2335,
2323,2311,2298,2286,2273,2261,2248,2236,2223,2211,
2198,2186,2173,2161,2148,2135,2123,2110,2098,2085,
2073,2060,2048,2035,2022,2010,1997,1985,1972,1960,
1947,1934,1922,1909,1897,1884,1872,1859,1847,1834,
1822,1809,1797,1784,1772,1760,1747,1735,1722,1710,
1697,1685,1673,1660,1648,1636,1623,1611,1599,1587,
1574,1562,1550,1538,1526,1514,1501,1489,1477,1465,
1453,1441,1429,1417,1405,1393,1381,1370,1358,1346,
1334,1322,1311,1299,1287,1276,1264,1252,1241,1229,
1218,1206,1195,1183,1172,1161,1149,1138,1127,1116,
1105,1093,1082,1071,1060,1049,1038,1027,1017,1006,
995,984,973,963,952,941,931,920,910,900,
889,879,869,858,848,838,828,818,808,798,
788,778,768,758,749,739,729,720,710,701,
691,682,672,663,654,645,636,627,618,609,
600,591,582,573,565,556,547,539,530,522,
514,505,497,489,481,473,465,457,449,441,
433,426,418,410,403,395,388,381,373,366,
359,352,345,338,331,324,318,311,304,298,
291,285,279,272,266,260,254,248,242,236,
230,224,219,213,207,202,197,191,186,181,
176,171,166,161,156,151,146,142,137,133,
128,124,120,115,111,107,103,99,96,92,
88,85,81,78,74,71,68,64,61,58,
55,53,50,47,44,42,39,37,35,32,
30,28,26,24,22,20,19,17,15,14,
12,11,10,9,8,7,6,5,4,3,
2,2,1,1,1,0,0,0,0,0,
0,0,1,1,1,2,2,3,4,5,
6,7,8,9,10,11,12,14,15,17,
19,20,22,24,26,28,30,32,35,37,
39,42,44,47,50,53,55,58,61,64,
68,71,74,78,81,85,88,92,96,99,
103,107,111,115,120,124,128,133,137,142,
146,151,156,161,166,171,176,181,186,191,
197,202,207,213,219,224,230,236,242,248,
254,260,266,272,279,285,291,298,304,311,
318,324,331,338,345,352,359,366,373,381,
388,395,403,410,418,426,433,441,449,457,
465,473,481,489,497,505,514,522,530,539,
547,556,565,573,582,591,600,609,618,627,
636,645,654,663,672,682,691,701,710,720,
729,739,749,758,768,778,788,798,808,818,
828,838,848,858,869,879,889,900,910,920,
931,941,952,963,973,984,995,1006,1017,1027,
1038,1049,1060,1071,1082,1093,1105,1116,1127,1138,
1149,1161,1172,1183,1195,1206,1218,1229,1241,1252,
1264,1276,1287,1299,1311,1322,1334,1346,1358,1370,
1381,1393,1405,1417,1429,1441,1453,1465,1477,1489,
1501,1514,1526,1538,1550,1562,1574,1587,1599,1611,
1623,1636,1648,1660,1673,1685,1697,1710,1722,1735,
1747,1760,1772,1784,1797,1809,1822,1834,1847,1859,
1872,1884,1897,1909,1922,1934,1947,1960,1972,1985,
1997,2010,2022,2035
};


 
void setup() {
// -------------------------------------------------------------
// default pins on Wave shield connected to DAC
pinMode(DATAOUT,     OUTPUT);
pinMode(SPICLOCK,    OUTPUT);
pinMode(SLAVESELECT, OUTPUT);
pinMode(LDAC, OUTPUT);

// seems to put the DAC in known state, but zero worked too!
// sendIntValueSPI(1000);
 sendIntValueSPI(0);
 
// basically keep this line low for the DAC to output signal is what I read
digitalWrite(LDAC,LOW);

// start serial interface
Serial.begin(9600);
}

// this is the routine that clocks a word of data to the DAC using SPI type transfer logic 
void sendIntValueSPI(int value) {
// -------------------------------------------------------------
 
// initiate data transfer with 4921
digitalWrite(SLAVESELECT,LOW);
 
// send 4 bit header
sendSPIHeader();
 
// send data
for(int i=11;i>=0;i--){
digitalWrite(DATAOUT,((value&(1<>i);
sendSPIClock();
}
 
// finish data transfer
digitalWrite(SLAVESELECT,HIGH);
}

// top of first byte of pair is commands for DAC
void sendSPIHeader() {
// -------------------------------------------------------------
// bit 15
// 0 write to DAC *
// 1 ignore command
digitalWrite(DATAOUT,LOW);
sendSPIClock();
// bit 14 Vref input buffer control
// 0 unbuffered *
// 1 buffered
digitalWrite(DATAOUT,LOW);
sendSPIClock();
// bit 13 Output Gain selection
// 0 2x
// 1 1x *
digitalWrite(DATAOUT,HIGH);
sendSPIClock();
// bit 12 Output shutdown control bit
// 0 Shutdown the device
// 1 Active mode operation *
digitalWrite(DATAOUT,HIGH);
sendSPIClock();
}

// basic clock of each bit with is routine
void sendSPIClock() {
// -------------------------------------------------------------
digitalWrite(SPICLOCK,HIGH);
digitalWrite(SPICLOCK,LOW);
}

// some simple wave forms for testing

void loop() {
// -------------------------------------------------------------


/*
// triangle wave
for (int i=0; i<25; i++)
{
  sendIntValueSPI(i*160);
}
for (int i=24; i>=0; i--)
{
  sendIntValueSPI(i*160);
}
*/
/*
// precision triangle wave
for (int i=0; i<=4095; i++)
{
  sendIntValueSPI(i);
}
for (int i=4095; i>=0; i--)
{
  sendIntValueSPI(i);
}
*/

//sine wave lookup
for (int i=0; i< (sizeof(sineLookup)/sizeof(int)); i++)
{
  // according to the doc, you cannot simply access data stored in the program mem like you would in data mem, so you must use the ATMEL functions to move data so you can use it.
  
  unsigned int tabVal = pgm_read_word_near(sineLookup + i);
//  Serial.print(i);
//  Serial.print(", ");
//  Serial.println(tabVal);
  sendIntValueSPI(tabVal);
}

/*
//square wave

interval = 0;
for (int i=0;  i < 50; i++) sendIntValueSPI(interval);
interval = 4095;
for (int i=0;  i < 50; i++) sendIntValueSPI(interval);
*/


//  for (interval=0; interval < 4096; interval++)
//  {
//   sendIntValueSPI(interval);

//  }
}

 

Dual monitor setup ideas, great price on a useful base monitor stand: Planar 997-5253 at Buy.com

This week [1st week January 2011], Buy.com has a pretty good deal on a desktop monitor stand that will get a dual monitor setup working for your desktop. Here is the link that is good for a least a week more. I paid thirty dollars more for the same unit at Amazon.com a while back, this is 'all in' with same shipping options and taking into account that Buy.com charges CA sales tax where Amazon.com does not. I am amazed at the shipping efficiency that Buy.com has, I ordered a 2nd one of these from Buy.com yesterday with their cheapest shipping option, free, and it was delivered via Fedex Home Ground the next afternoon. Clearly your physical location relative to Buy.com's logistics sites will make a difference, but wow!

I'm a big fan of portrait monitor orientation as you can see by the second picture below. What is nice about the Planar dual monitor stand is that is able to handle monitors up to 24 inches in either landscape, portrait or a combination. The ability for Windows, Linux and Mac OS X to handle multiple monitors and monitors turned 90 degrees [or 270 degrees] has greatly improved over the years. I still find Apple's OS X operating system to handle it the best 'out of the box'.  Much of their advantage is that they control both the hardware and video display drivers. In Windows and Linux you often have to deal with one or more third party video card drivers to get it working. That said, my configurations on Ubuntu Linux 10.02 work really well. I have been using nVidia cards for a while and they works solidly, but do expect to spend more time in the setup phase than you will on OS X.

The Planar 997-5253 stand is really easy to setup and is very stable on your desk. I'm using 21 inch monitors in portrait orientation and there is no way they will tip over. In the past, I've used stands that attached to the sides of desks or into drilled holes. While these are the ultimate in stability, they are more difficult to get a good ergonomic setup.

The price and selection of LCD monitors is wide open now, so you have to shop around for price point, size and display quality. The most important item for the dual monitor setup is to make sure the monitors you buy have the ability to remove their standard base and mount via the industry standard 'VESA 100 mm by 100 mm' or 'VESA 75 mm by 75 mm' third party mounting option. Be careful with some of the lower cost LCD monitors, as they do NOT have this option. Apple's LCD monitors do not have this option either, though people have hacked the Apple monitor mounts to make them work. So for a OS X dual monitor configuration; Mac Mini, Mac Book Pro, or Mac Pro I recommend using non-Apple monitors. You might wonder how you drive multiple monitors on a Mac Book Pro or Mac Mini, if you search Google.com, you will find a number of people that have made this work using various configurations of the internal video card and cables. For my configuration on a MacBook Pro, I went with a external USB video card device from DisplayLink.com . Their latest OS X drivers support display rotation, the video quality on the DisplayLink device that I have not as high a quality as the built in video card of the MacBook Pro, but has been fine for my old eyes and has been running solidly with no memory leaks or crashes. On the Linux machine, where I do most of my work, I use nVidia video cards that have dual monitor support build in. The Apple MacPro has similar video cards available. Having a powerful video card with dual DVI or HDMI monitor support is the ideal machine to run. But I can say that my MacBook Pro configuration, which is really a THREE monitor solution, since the display on the notebook works as well. It is solid and a good setup for email, coding and document review.