Data serialization for embedded platforms: ASN.1, JSON, Protocol Buffers....

Started by pozz in comp.arch.embedded3 months ago 1 reply

It's a long time I work with embedded platforms, however I never used a well-defined and "standard" data serialization format. I often had the...

It's a long time I work with embedded platforms, however I never used a well-defined and "standard" data serialization format. I often had the need to exchange data between platforms (Wifi, Ethernet, RS485...) and I always find a custom solution. I perfectly understood the problem with this approach. Keeping the two (or more) side synchronized is very difficult and error-prone. When the...


Two wires bus for data and power

Started by pozz in comp.arch.embedded3 years ago 16 replies

There are many commercial solutions for home-automation systems that are based on a two wires bus both for bidirectional data and for powering...

There are many commercial solutions for home-automation systems that are based on a two wires bus both for bidirectional data and for powering the modules. The number of connected modules could be high, 100 or more. What is the technology of those kind of buses? Are they simple half-duplex RS485? In this case, how the power can be distributed on the same wires of data? Is the protocol ...


Best embedded board

Started by S in comp.arch.embedded12 years ago 4 replies

Hi, We need a good embedded CPU board for our next project. It must be equipped with a relative fast processor, lots of RAM, Ethernet...

Hi, We need a good embedded CPU board for our next project. It must be equipped with a relative fast processor, lots of RAM, Ethernet (TCP/IP), optionally WiFi, Flash-card interface, at least 3 RS232/RS485 ports, some digital I/O, low power and last be not least low cost. The CPU board will be installed on our custom motherboard, where some of our custom hardware will be located. ...


HDLC Normal Responde Mode implementation

Started by Anonymous in comp.arch.embedded6 years ago 7 replies

I was searching for a reliable and simple protocol for a multidrop master/slave RS485 network. Reliable means it should work well if some...

I was searching for a reliable and simple protocol for a multidrop master/slave RS485 network. Reliable means it should work well if some errors occur, so it should provide retransmissions and detection of frame duplication. As soon as I read about HDLC in Normal Responde Mode, I loved it immediately. It is exactly what I wanted. http://en.wikipedia.org/wiki/High-Level_Data_Link_Cont...


Ethernet Polling vs Broadcasting on an Embedded device

Started by linuxdude in comp.arch.embedded15 years ago 18 replies

Hello guys, I have asked to design a test system for an Ethernet enabled weather station. At this point, these weather stations are nothing...

Hello guys, I have asked to design a test system for an Ethernet enabled weather station. At this point, these weather stations are nothing but 2 PCs running Linux on it and they constantly read weather related information through some sensors. Eventually they will be replaced with a miniature embedded Linux device (yet to be designed!). I have worked extensively with 1/2 duplex RS485 n...


race condition? between relays and 89C51 uC

Started by Mak in comp.arch.embedded8 years ago 7 replies

hello everyone, I have a RS485 based slave relay driver with 8 relays. The relays turn on at logic 0. Since the 89C51 has all ports as HIGH...

hello everyone, I have a RS485 based slave relay driver with 8 relays. The relays turn on at logic 0. Since the 89C51 has all ports as HIGH during reset, my relays should remain off. The problem that I am facing is that when I turn the power supply on, all the relays turn on momentarily and then back off. Is there a race condition during which the microcontroller is not gaining control of ...


Making a connection with Android device through USB

Started by pozz in comp.arch.embedded3 years ago 4 replies

I'm trying to find a way to make a connection between a custom MCU-based device (accessory) and an Android device (smartphone or tablet). The...

I'm trying to find a way to make a connection between a custom MCU-based device (accessory) and an Android device (smartphone or tablet). The goal is to exchange some data as with the old and good asyncronous serial (RS232/UART/RS485). My goal is to let the user configure the device through its smartphone, without power up a laptop or using local HMI (that will be surely worse than An...


Asyncronous serial bus network with UART and CAN transceiver

Started by pozz in comp.arch.embedded4 years ago 2 replies

I read the following page: http://xpcc.io/api/group__sab2.html The author suggests to use a CAN transceiver, instead of a RS485 half-duplex...

I read the following page: http://xpcc.io/api/group__sab2.html The author suggests to use a CAN transceiver, instead of a RS485 half-duplex transceiver, to create a serial multi-drop bus with nodes featuring normal UART peripherals. This should avoid the use of a third pin for direction control. What do you think? Does this solution works without problems? I think the control of the...


SBC6845 board based on AT91SAM9G45

Started by Talor Snow in comp.arch.embedded8 years ago

I find a board is very strong because it has so many things below: I am searching a board based on AT91SAM9G45 processor. 1. It must be all...

I find a board is very strong because it has so many things below: I am searching a board based on AT91SAM9G45 processor. 1. It must be all industry designed. Working temperature is -40-70 Celsius, not 0-70 Celsius. 2.Have 16 GPIOs, 5 USARTs, RS485, CAN, 2 methods of power which is +12V, ADC and other interface. 3.Supports 10.4"LCD, 4.3"LCD and 7" LCD. 4.Power consumption is below...


Recommend hardware with USB, RS232, A2D, and more...

Started by Rob in comp.arch.embedded15 years ago 1 reply

Looking for a processor board with: - USB Host port (Full-speed, USB v1.1 minimum), - 2x Serial ports (RS232, RS485), - 12-bit A/D converter...

Looking for a processor board with: - USB Host port (Full-speed, USB v1.1 minimum), - 2x Serial ports (RS232, RS485), - 12-bit A/D converter (under 2k samples/s) - Several general purpose I/O or parallel port. - Real-time clock (battery backed) and timers. - Low power consumption; few Watts. - Support an embedded operating system, like Linux preferably (but not essential). - Flash and RAM...


How to define task in RTOS

Started by ckto in comp.arch.embedded14 years ago 7 replies

Hi all, I am going to use freeRTOS to do project, which has the following hardwar module. - 128x64 dot mono LCD graphic module - 4 key...

Hi all, I am going to use freeRTOS to do project, which has the following hardwar module. - 128x64 dot mono LCD graphic module - 4 key (direct key configure) - IrDA for printing - doing ADC via I2C interfaced ADC every 500ms The function of the device is; - User can use the key and display to read the DAC value - PC can request the ADC value / Key status / LCD status via RS485 / USB...


RS458 Cabling

Started by bfranklin825 in comp.arch.embedded10 years ago 1 reply

I have a piece of equipment that uses RS485 with RJ45 jacks and I was wondering if I needed special cabling with only 4 of the wires...

I have a piece of equipment that uses RS485 with RJ45 jacks and I was wondering if I needed special cabling with only 4 of the wires phyically connected in the jack or could I just use regular CAT5 Ethernet cabling with all eight wires present? The specs that I have for the cable only list 4 wires, but they are in the same order and place as a regular CAT5 Ethernet cable. The cable will go between...


How do i interface with the processor and acheive 10 Mbps?

Started by Anonymous in comp.arch.embedded11 years ago 6 replies

I found that many RS485 transceivers can transmit data at the rate of 10 Mbps. My application requires that speed to communicate for a short...

I found that many RS485 transceivers can transmit data at the rate of 10 Mbps. My application requires that speed to communicate for a short distance (2 feet or 0.5 metres or so). Processors have UART which can transmit at 115kbps and not more. How do i acheive 10Mbps when the normal 32 bit processors could transmit at only 115kbps? I found one application note "AN3884-how fast can u go...


Problems with MC9S12NE64 and some switches

Started by john...@gmail.com in comp.arch.embedded13 years ago 2 replies

Hello! We are using a MC9S12NE64 for a RS485-> Ethernet router. we've experiencing problems with certain network switches. We get...

Hello! We are using a MC9S12NE64 for a RS485-> Ethernet router. we've experiencing problems with certain network switches. We get packet losses when we connect the router to some switches, the packages gets sent from the MC9S12NE64 but don't end up at the receiver. But with other switches the exact same application works fine. If connect a network hub between the MC9S12NE64 and the switch


RS485: two transceivers

Started by aleksa in comp.arch.embedded8 years ago 35 replies

I have two CPUs, master and slave. They are (will be, actually) connected with one SN75176B IC on each side, with two wires connecting...

I have two CPUs, master and slave. They are (will be, actually) connected with one SN75176B IC on each side, with two wires connecting them. After reset, the master will be in transmit mode, slave in recv mode. When the master sends a command to slave, the master will switch into recv mode and slave into transmit mode. Now, what happens while they are switching? At one moment, both si...


Help needed in ATMEL ARM9 microcontroller

Started by bbaskaran in comp.arch.embedded13 years ago 2 replies

Dear All, I am using ARM9 based ATMEL AT91RM9200 microcontoller for a communication project. I am using a custom designed PCB. Problem is...

Dear All, I am using ARM9 based ATMEL AT91RM9200 microcontoller for a communication project. I am using a custom designed PCB. Problem is when i am receiving data via serial port, some times the controller got hang up. Need to restart every time. I am using RS485 communication and receive data via ttyS3 port. Presently i am receiving data in non-cannonical mode. controller have ...


Debugging of 9-bit mode

Started by arslan in comp.arch.embedded11 years ago 8 replies

I am working on a master slave architecture based on RS485 protocol in 9-bit mode (with backbone configuration). The master is 80c196kd and the...

I am working on a master slave architecture based on RS485 protocol in 9-bit mode (with backbone configuration). The master is 80c196kd and the slaves are all 8051 microcontrollers. The slaves are in fact sensors and actuators. Now the problem in working with 9-bit mode is that the debgging becomes tough, normaly i use MATLAB for observing the data (when in 8-bit mode). Matlab does not support...


GUI interface for embedded gadgets

Started by pozz in comp.arch.embedded4 years ago 11 replies

Most of my electronics gadgets must be configured by the user. There many UI (User Interface) avaiable and each has pros and cons: - voice...

Most of my electronics gadgets must be configured by the user. There many UI (User Interface) avaiable and each has pros and cons: - voice assisted guide with a keypad - display and keypad - touch display - serial channel (RS232/RS485/USB/Ethernet) connected to a PC - ... Many time I choose to provide a simple RS232/USB port on my gadget, to keep its cost low. When the user wants to co...


Connection in exterior concrete pad

Started by Robert Adsett in comp.arch.embedded8 years ago 24 replies

A company I'm working with is developing an application the needs to connect power and data (standard 110V/60Hz and RS485 type data) on a flat...

A company I'm working with is developing an application the needs to connect power and data (standard 110V/60Hz and RS485 type data) on a flat exterior concrete pad. We have connectors that we think will do the job (IP68 with power and data) but we are looking for a connection box that can be cast in place in the concrete for the pad side of the connection. It has to be flush with the con...


Recomendations for a modbus library

Started by David Jones in comp.arch.embedded12 years ago 2 replies

I have just been presented with a little job. I need to make a converter between modbus protocol and a proprietry one. They are thinking of...

I have just been presented with a little job. I need to make a converter between modbus protocol and a proprietry one. They are thinking of using the xnut [1] unit. I would have to write the code to make this convert the proprietry protocol to modbus over RS485. Their protocol is significantly different to modbus. Xnut runs linux. The xnut library does not support modbus (I think)....