Electrical Engineering

DarkHorse

02:57

how to set watermark interrupt?

The Photon

@DarkHorse What is a "watermark interrupt"?

DarkHorse

@ThePhoton Have you even used a sensor such as gyroscope or accelerometer?

The Photon

@DarkHorse I have not used a gyroscope or an accelerometer, but I have used many kinds of sensors.

DarkHorse

I think you are familiar with FIFO, right?

The Photon

Yes

In the context of a FIFO, I can guess what a watermark interrupt is.

DarkHorse

03:08

@ThePhoton okay

The Photon

In FIFO's I've worked with (not related to sensors at all), there was not "watermark" interrupt, but there were "almost full" and "almost empty" interrupts. IIRC, the levels were fixed and not adjustable.

DarkHorse

I have a gyroscope output data with 200 frame per second, and the FIFO length is 32 frame. so i want to get data with 10 times per second, and this means I must get data when it accumulate to 20 frame

so when 20 frame arrived in the FIFO, there is need to make interrupt and give notify, so that's watermark interrupt

At least, there is watermark interrupt for user set with gyroscope L3GD20, a three-axis digital gyroscope

The Photon

03:52

@DarkHorse, In the ST datasheet on page 33 I see a bit in CTRL_REG3 to enable or disable the watermark interrupt, and on page 36 there's a 5-bit field in FIFO_CTRL_REG to set the level.

@DarkHorse, notice the default in CTRL_REG3 is to have the interrupt disabled.

DarkHorse

@ThePhoton great. Indeed I have done that But seems to have a problem when connect with stm32 GPIO and NVIC setting

W5VO

@MLM Congrats on getting your FPGA project featured on HAD

The Photon

@DarkHorse What is an "NVIC setting"?

DarkHorse

04:08

I'm layman in microcontroller

so let me think how to express my thought

W5VO

04:36

It puts the data in the registers

The Photon

04:52

@W5VO Wha?

W5VO

there's some sort of a psycho reference

The Photon

@W5VO, I'm beginning to think you might be a Markov Chain text generator rather than a grad student in Arkansas.

MLM

@W5VO Thanks, I saw it about the same time you messaged: hackaday.com/2013/12/26/fubarino-contest-fpga-pong

2

I'm so happy :D

The Photon

@MLM sweet

W5VO

@ThePhoton I got some scotch for christmas

The Photon

05:06

@W5VO Nice. All I got was a shop-vac.

DarkHorse

:D cool

I got nothing for christmas

MLM

@W5VO Did you find the article earlier in the day? The reason I ask is because I came home and my site was down (ran out of memory). I wonder how long it was down for.

W5VO

@MLM no, I messaged when I saw it

MLM

06:04

Looks like a missed 4 hours of traffic (3 to 7). I gtg, night

AsheeshR

General question: On a RPi what does the SCL line do?

From what I understand, it provides the clock pulse to all connected devices.

tylerl

@AsheeshR yup. SCL is the clock line for the SPI bus

And I2C

...acutally, I think it's called SCLK on SPI.

AsheeshR

Ok, I am using airspayce.com/mikem/bcm2835 for I2C with a device.

Whenever the library program runs, it leaves the bus in an invalid state.

Any devices that were being detected before the library code started, disappear.

From a bit of testing and trial and error, I think the problem is in the function bcm2835_i2c_end which while exiting sets SCL pin in an INPUT state.

So, what I wanted to know is what state should the SCL pin be set to, or what state it is in by default.

I have been reading the BCM2835 datasheet, but its huge and I am not really sure what I should be looking for.

tylerl

06:24

In I2C, the clock line is bi-directional.

which doesn't fit neatly into the concept of strictly INPUT or OUTPUT

Here's some recreational reading on the subject:

I²C

I²C (Inter-Integrated Circuit, referred to as I-squared-C, I-two-C, or IIC) is a multimaster serial single-ended computer bus invented by Philips used for attaching low-speed peripherals to a motherboard, embedded system, cellphone, or other electronic device. Not to be confused with the term Two Wire Interface which only describes a compatible hardware interface. Since the mid-1990s, several competitors (e.g., Siemens AG (later Infineon Technologies AG, now Intel mobile communications), NEC, Texas Instruments, STMicroelectronics (formerly SGS-Thomson), Motorola (later Freescale), Inters...

The Photon

06:43

@tylerl but when your uC is not driving SCL low, it makes sense to put the uC pin in input mode so that 1. It will be undriven, and 2. the uC can detect if another device drives SCL.

tylerl

@ThePhoton right; so unless your uC is "controlling" the bus; driving the clock or pulling it down, it should be in INPUT mode.

AsheeshR

These are the options that I have:
BCM2835_GPIO_FSEL_INPT = 0b000, ///< Input
BCM2835_GPIO_FSEL_OUTP = 0b001, ///< Output
BCM2835_GPIO_FSEL_ALT0 = 0b100, ///< Alternate function 0
BCM2835_GPIO_FSEL_ALT1 = 0b101, ///< Alternate function 1
BCM2835_GPIO_FSEL_ALT2 = 0b110, ///< Alternate function 2
BCM2835_GPIO_FSEL_ALT3 = 0b111, ///< Alternate function 3
BCM2835_GPIO_FSEL_ALT4 = 0b011, ///< Alternate function 4
BCM2835_GPIO_FSEL_ALT5 = 0b010, ///< Alternate function 5
BCM2835_GPIO_FSEL_MASK = 0b111 ///< Function select bits mask

Currently, its SCL is being set to FSEL_INPT. I tried FSEL_OUTP, but that didnt help.

jippie

08:29

morning

angelatlarge

Morning! @jippie, I want to ask you something

jippie

I see Arduino and RPI-questions

angelatlarge

@jippie No, that's not it :)

jippie

@angelatlarge sure, let me grab a cup of coffee while you write

angelatlarge

@jippie Kewl. Have you ever bought a knock-off USBasp? Because I have, and I can't get it to work on my Ubuntu machine. USBtinyISP works fine, but this knock-off USBasp seem dead-ish. I am wondering if you have experience with things like this.

jippie

08:38

@angelatlarge no, sorry

@angelatlarge does the kernel recognize it?

angelatlarge

@jippie Yeah. I have it in my lsusb

jippie

do you get an error message when trying to use it? How are you trying to use it anyway?

angelatlarge

avrdude even finds it.

jippie

@angelatlarge what is the device name, what error do get?

angelatlarge

Yeah, standard-ish error message:
$ sudo avrdude -v -v -v -v -c usbasp -p m1284p
avrdude: auto set sck period (because given equals null)
avrdude: error: programm enable: target doesn't answer. 1
avrdude: initialization failed, rc=-1
Double check connections and try again, or use -F to override
this check.

jippie

08:40

I have to compile a list of 'known' avrdude errors some day

target doesn't answer? is that the microcontroller? it means you are talking to the programmer ...

angelatlarge

@jippie That would be good. I think it means "can't talk to your programmer" - I have a working USBtinyISP which I can compare it with. If it isn't connected to the MCU I get a different error.

I think it means programmer, on the basis of USBtinyISP comparison.

Though I do agree that target sure sounds like "the thing you want to program"

jippie

what does dmesg say? dmesg | grep -i usbasp -C3 or something similar

and does it exist as a device file? ls -l /dev/usbasp

angelatlarge

Do you mean w.r.t to plugging it in? Yeah, it shows up in lsusb as
Bus 002 Device 012: ID 16c0:05dc VOTI shared ID for use with libusb

jippie

Ah the other Dutch guy, right. I don't do warranties on his hardware ;o)

angelatlarge

Oh, huh, it does show up as USBasp in dmesg! Wow

[ 6563.450278] usb 2-1.2: new low-speed USB device number 12 using ehci-pci
[ 6563.550450] usb 2-1.2: New USB device found, idVendor=16c0, idProduct=05dc
[ 6563.550459] usb 2-1.2: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[ 6563.550464] usb 2-1.2: Product: USBasp
[ 6563.550470] usb 2-1.2: Manufacturer: www.fischl.de

jippie

08:46

@angelatlarge and the ls ?

angelatlarge

I am not seeing anything relevant in /dev

@jippie Do you still want me to pry it apart so that I can find the manufacturer's website + product page?

jippie

@angelatlarge pry it apart!? this isn't eevblog!

We respect carefully assembled electronics here

angelatlarge

aliexpress.com/store/product/…

(pried it apart for the firth time or so)

BTW, did you settle on your fancy scope?

jippie

why are they using this huge controller if they only use 6 pins?

angelatlarge

It's an ATmega8

That's how USBasp design has it

It's a bit like you like doing things: using an Arduino to program an Arduino

jippie

08:53

I've seen ATtiny2313 implementations ..

Nature is calling

rather urgently

angelatlarge

Ok, go talk to nature. I'll keep sipping my beer

BTW, when can we put Kessner back into David? That would make me really happy

jippie

?

angelatlarge

Oh and after you are done communing with @Nature I want to ask you a bit more about how you run your Ubuntu

jippie

have you tried an analyzer on the MISO/MOSI/RESET pins? Is activity on them?

@angelatlarge on a quad core Intel

dual monitors, a smaller one and a bigger one.

angelatlarge

No, I have not. Here's one thing I did try: running avrdude -v -v -v -v with USBtinyISP plugged in and no MCU. The thing is I get some commands output. With usbasp I get nothing.

Like this:
avrdude: Using SCK period of 10 usec
CMD: [ac 53 00 00] [ff ff ff ff]
CMD: [ac 53 00 00] [80 00 00 00]
avrdude: initialization failed, rc=-1
Double check connections and try again, or use -F to override
this check.

@jippie what desktop manager/environment do you run?

jippie

09:05

kubuntu /kde

angelatlarge

Is dolphin the default file browser there?

jippie

:-|

dolphin is more like a file manager

oh that is what you typed

@angelatlarge yeah I use it regularly

angelatlarge

I installed it here, it is better than the new stock file mangler but it has its issues too

jippie

@angelatlarge ?

angelatlarge

yeeeaas?

Ok, going to bed. goodnight!

jippie

09:15

@angelatlarge what happens if you run avrdude as root?

oh

night

@AnindoGhosh Energia 0101E0011 (12/17/2013) is updated

abdullah kahraman

Hi

David