Raspberry Pi Forums

lilzz

I used pi to control IoT things at home. I have 3 raspberry Pi to control various things. I have a router. so if I want an APP from outside to control things at home, it sends a http request with my home router IP address. 1)router gets the http request from outside and I want the router to broadcas...

lilzz

An atom has a nucleus which is positively charged due to it's one or more protons. Around the nucleus swarms one or more negatively charged electrons. The atom as a whole is neutral, the positive and negative charges balance each other. .... Of course there is a lot more to it than I mention above....

lilzz

I want to design a pi based project , in a vaccum system, I put in some pure elements. I then bombard the element with 10,000V electron gun. Basically enough voltage and energy to drive away all its electrons of the element. I have a positive electrode inside to collect all those knocked out electro...

lilzz

Somebody wrote it, it's used by the linker ld to tell it how to link object files. Normally ld will use a default linker script but if you pass a linker script to it it will use that instead. http://www.math.utah.edu/docs/info/ld_3.html So, anytimes you wrote a program, and produce some object file...

lilzz

And the user program would referenced those functions programmed into the ROM.
How does the linker hook up and referenced those functions in the ROM?
Anyone seen an example for that?

lilzz

If in a project there's xxx.ld linker script, How's it being generated or being used?

What's the syntax to input the xxx.ld script to the GCC toolchain?

lilzz

Normally flash memory, rom memory can be memory mapped to DRAM main memory. But since flash memory could be bigger than DRAM main memory, then how it could be mapped from something bigger to something smaller? I read some where the main processor for Pi has internal sram, is that means the system do...

lilzz

I don't want the original firmware changed.

I just want to run an user program (C code) after the system got booted up.

how to do that?

lilzz

Ok, I connect to a gateway and acquired a IP address. Verifed that.
I try to connect to google.com

AT+CIPSTART=4,”TCP”,”www.google.com”,80

it gives back Link Error.

what does that mean?

lilzz

http://room-15.github.io/blog/2015/03/2 ... reference/

for example, if I want connection to yahoo.com
what's the AT command for that?

lilzz

Ok, I set the baud rate to 115200, I see something now.

but I type AT, and hit enter button.

I expect to see OK as response but nothing happened.

what's CR+LF? same as enter button?

lilzz

OK, I got something back like this.

But I can't type any command. What does this mean from the picture I shown? Is the communication OK? I attached a ESP8266 wifi module to the CP201x.

lilzz

OK, my putty is finally launched now.

but it's a blank. it has a small green rectangular shape and nothing else.

I try to type in something but nothing shown.

lilzz

I can't add myself to dialout group.
sudo usermod -a -G dialout lilzz

then I check with groups
dialout still not there

lilzz

well, I did
groups
lilzz adm sudo dip plugdev lpadmin

so, I added

useradd -G dialout lilzz

but it complains
useradd: user 'lilzz' already exists

lilzz

dmesg | grep tty
usb 6-2: cp210x converter now attached to ttyUSB0

then I started Putty
Putty configuration
/dev/ttyUSB0 baud:9600

connect (open)

But it complains unable to open serial port.

lilzz

I trying to copy mathmatical formula from pdf file to word document, but it's crooked and lost the subscript and style of the font from pdf to word once I do a copy-n-paste. How do I get around this?

lilzz

Raspbian is full linux image that take up too much space. I can't have that. Why not? SD card space is cheap. Let's just say for argument sake, I want to save that SD card money. Just have onboard flash memory. I need tiny footprint on OS. FreeRTOS is the smallest foot print I could find.

lilzz

I need the simplest OS on a Pi that can allow an user to make a HTTP call.
Raspbian is full linux image that take up too much space. I can't have that.

Is FreeRTOS the simplest OS I can have to make a http call base on user input?

lilzz

this project processing happens in the background via Timer 2 interrupt. 2mS sample rate. 1)600 micro seconds? or miliseconds. volatile int IBI = 600; // holds the time between beats, the Inter-Beat Interval 2)512mV? I assumed volatile int P =512; // used to find peak in pulse wave

lilzz

delay(100)

that means delaying 100ms.

where does it calibrated such each unit is equivalent to 1ms? not 1us . I can't find anywhere in code.

DOes this relate to crystal or system clock(for example, 16Mhz)? or instruction cycle period?

lilzz

y.tab.c:557:1: error: duplicate ‘extern’ //extern YYSTYPE yylval; ^ make[1]: *** [pat_decl_y.lo] Error 1 make[1]: Leaving directory `/home/lilzz/alliance-5.0/ppt/src' make: *** [all-recursive] Error 1 lilzz@lilzz-Latitude-E6400:~/alliance-5.0/ppt$ //extern YYSTYPE yylval I already have that // whic...

lilzz

Code: Select all

if $jsr CheckCDROM $cdPathDir; then 
  $jsr EchoN "${NL}Located CDROM at $cdPathDir ${NL}"
else

waht's this EchoN and why in bracket? ${NL}

lilzz

jsr='' execPlat=`$jsr GetPlat` if [ "X$execPlat" = "XUNKNOWN" ]; then echo "Error: Unsupported platform.${NL}${suppPlats}" exit 1 fi GetPlat () { if [ -x /bin/uname ]; then unameResult=`/bin/uname -a` platForm=`echo $unameResult | awk '{print $1}'` } 1) GetPlat is a function, but why put '$jsr GetP...

lilzz

kernel tick frequency (1000 Hz)t
which is 1kHz.

But the Broadcom Chipset for Pi is 900Mhz

What's the relationship between the two? Why kernek tick frequency is lower than chipset frequency.?

Search found 411 matches

IoT home project setup

Re: what happen when element got stripped of all its electro

what happen when element got stripped of all its electrons.

Re: How does Linker script are being generated and used.

If some common used functions being programed into a ROM.

How does Linker script are being generated and used.

Is Pi's flash memory memory mapped?

How to run an user program on ESP8266 Wifi module

Re: What's the AT command for URL of ESP8266 Wif module

What's the AT command for URL of ESP8266 Wif module

Re: Installing a CP210x USB to Serial converter

Re: Installing a CP210x USB to Serial converter

Re: Installing a CP210x USB to Serial converter

Re: Installing a CP210x USB to Serial converter

Re: Installing a CP210x USB to Serial converter

Installing a CP210x USB to Serial converter

I can't copy-n-paste mathmatical formula from PDF.

Re: what's the simplest OS a Pi can have to make Http call?

what's the simplest OS a Pi can have to make Http call?

Unit of data and time

The delay() function

why this compilation error

Re: Linux Scripting

Linux Scripting

what's a kernel tick frequency?