Show Posts
Pages: [1] 2 3 ... 16
1  Using Arduino / Programming Questions / Re: upload firmware over half duplex RS-485 on: February 28, 2014, 09:19:49 pm
It worked for me.
2  Using Arduino / Programming Questions / Re: upload firmware over half duplex RS-485 on: September 12, 2013, 02:23:38 pm
Thank you for answering my question.  For the reset, I will just jerry-rig something up to cycle the power.  That won't be a problem.  BTW, I'll have to modify the bootloader to control the TX enable pin of the RS-485 transceiver which shouldn't be a problem either.  Thank you!
3  Using Arduino / Programming Questions / upload firmware over half duplex RS-485 on: September 12, 2013, 11:52:30 am
Does the Arduino bootloader work in a half duplex manner?  I have used the Arduino bootloader for my own personal projects with great success.  I have a new project that has a "two-wire" (half-duplex) RS-485 serial interface.  Once the board is in its housing, the ISP connector is difficult to access.  I was wondering could I use the RS-485 interface to program the chip.  I'm using the hardware UART of the chip for the RS-485 interface.  The essence of my question is can the bootloader work in a half duplex manner.
4  Using Arduino / Programming Questions / Re: Problem with ModbusMaster library on: June 06, 2013, 10:37:53 am
Post as much of the code as you can.
5  Using Arduino / Programming Questions / Re: T0/T1 internal pull-ups on: May 02, 2013, 03:29:33 pm
It works!

Code:
void setup() {
  Serial.begin(9600);
  pinMode(5, INPUT_PULLUP);
  TCCR1A = 0;
  TIMSK1 = 0;
  TIFR1  = 0;
  TCCR1B = _BV(CS12)
         | _BV(CS11);
  TCNT1 = 0;
}

void loop() {
  Serial.println(TCNT1);
  delay(1000);
}
6  Using Arduino / Programming Questions / Re: T0/T1 internal pull-ups on: May 02, 2013, 02:58:49 pm
Pull-ups are for *inputs*.  Clock sources are *outputs*.

I think there is some confusion...  T0 and T1 are inputs (see section 14.3.3 of the datasheet).  I probably should have said that I want to select them as the clock source. 

And a base resistor connects between a pin and the base of a transistor.  A pullup connects between the pin and Vcc.  How that can replace a base resistor I'm not quite sure...

I want T0 or T1 to be held high while the transistor is off and pulled low when the transistor is on.  The transistor in this case is a photo-interrupter.
7  Using Arduino / Programming Questions / Re: T0/T1 internal pull-ups on: May 02, 2013, 02:38:15 pm
Why? When the pins are outputs/clock sources, the 40mA drive capability will far outweigh the 0.25mA an pullup can offer.

I want to connect it to the collector of a transistor without having an external resistor.
8  Using Arduino / Programming Questions / T0/T1 internal pull-ups on: May 02, 2013, 02:04:57 pm
Is it possible to use the internal pull-ups on pins T0 and T1 while using them as clock sources?  If it matters, I'm using the ATmega328P chip.
9  Using Arduino / Networking, Protocols, and Devices / Re: DHCP testing tool on: January 29, 2013, 02:01:06 pm
http://www.vercot.com/~serva/
10  Using Arduino / Networking, Protocols, and Devices / Re: DHCP testing tool on: January 29, 2013, 11:24:29 am
Good questions... I will try different DHCP server implementations, but I was interested in see how it would handle non-typical DHCP information.  It has been years since I have read about what can be put in DHCP packets.

The program named Serva looks interesting.
11  Using Arduino / Networking, Protocols, and Devices / Re: DHCP testing tool on: January 28, 2013, 03:41:01 pm
I realize I wasn't clear about what I was asking.  I want to try different DHCP server settings to see if my device handles them correctly.  DHCP can do a lot more than just hand out IP addresses.  I'm afraid that my device will work fine with my DHCP server, and when it becomes time to ship it to the customer, it won't work on their server.

I know and use Wireshark.  I've been using it since it was named Ethereal. 
12  Using Arduino / Networking, Protocols, and Devices / DHCP testing tool on: January 28, 2013, 02:41:01 pm
Is there a recommended software program to use to test/exercise the networking stack particularly DHCP?  I'm going to develop an Ethernet based product, and currently, I'm creating a plan for the project which includes how it will be tested.
13  Using Arduino / Programming Questions / Re: Twittering with Arduino+Ethernet Shield on: January 25, 2013, 04:07:13 pm
I am using my universities network so due to restrictions, I cannot use DHCP to automatically assign the IP hence iam doing it manually.
Ok i declared the DNS server IP:

IPAddress myDns(168, 126, 63, 1);
Ethernet.begin(mac, ip, myDns);

It gives the following result:

117.17.80.199
255.255.255.0
117.17.80.1
168.126.63.1
connecting ...
HTTP/1.0 403 Forbidden
Content-Type: text/html; charset=utf-8
Cache-Control: no-cache
Vary: Accept-Encoding
Date: Thu, 24 Jan 2013 01:19:45 GMT
Server: Google Frontend

Error 403 - Status is a duplicate.
failed : code 403

what might be wrong now?

There maybe a problem in the future if some other computer starts using that assigned IP assigned.  It would be nice if the university would give you another IP address for your *second* computer.
14  Using Arduino / Programming Questions / Re: eeprom_update_block missing eeprom.h on: January 22, 2013, 12:06:13 pm
Those "update" functions came out in version 1.7.0 of avr-libc.  Arduino is using an older avr-libc (v1.6.4).
15  Using Arduino / Programming Questions / Re: Sketch different behavior using external power instead of USB cable on: January 22, 2013, 11:53:11 am
You can measure AREF indirectly by measuring the internal voltage reference.  This can be done by applying a known voltage to AREF and measure internal voltage reference.  This will tell you the voltage of the internal voltage reference.  Store this value somewhere so that you can measure it again in the future and back calculate the voltage on AREF.  Vcc and AREF are connected through a low-pass filter.  There is no need for a voltage divider.
Pages: [1] 2 3 ... 16