My problem:
I have connected a VEML6030 (Ambient Light Sensor from Vishay) to my µC.
If I want to read this sensor, I only get 0x0000 as an answer.
I'm programming in c on a Renesas r5F104GK.
I used Applilet as a code generator.
I have the data sheet and an application note as documentation. I have also already spent days searching online - unfortunately unsuccessful so far.
I also have a Lis3DH sensor on my PCB, which is connected to the same I²C bus.
I can separate both components from the bus with a jumper.
What I have already achieved:
Depending on the level of the ADDR pin, I see an ack on the bus.
identify veml6030
The communication with the Lis3DH works (read & write)
I get protocol-compliant Ack / NACK from the sensor.
The system is operated at 3V
If I try to read output, I only get 0x000:
Output
During the tests I am sure that only the VEML6030 is contacted.
I would be very happy if someone here could share their experience with the VEML6030 and, if necessary, have a tip on what I'm doing wrong.
In the end, I'm sure that the problem is in front of the monitor ;)
Update (#Lundin)
How can I move my ticket to electronics.stackexchange.com?
Unfortunately I can only publish a part of the schematic
2.1) SDA & SCL have got 10k Pullups
2.2) SDA is connected to µC Pin 18 (P14/RxD2/SI20/SDA20/TRDIOD0/(SCLA0))
2.3) SCL is connected to µC Pin 17 (P15/PCLBUZ1/SCK20/SCL20/TRDIOB0/(SDAA0))
2.4) INT is connected to µC Pin 36 (P140/PCLBUZ0/INTP6)
The Connector at ADDR is just used to get the correct footprint on the PCB. In real it is a Jumper with 3 pins.
P.S.: Solved Communication
enter image description here
I hope this is the correct way now.
My problem is solved.
I've to send only a "Start".
Related
I need connect my raspberry pi 4 model b with a servo via UART, but it is possible only via 1 wire. That means I must connect pin TX and RX together. In order to do so, I must have a way how to manually disable only TX or RX in my C program.
I am able to easily disable RX thanks to termios.h library, but I didn't find any way how to disable TX.
I was trying to disable it through this
tcflow(fd_myUART, TCOOFF); // it should suspend output
But that didn't work, so I thought that maybe if I change the pin of TX to INPUT, it will change the pin from UART to GPIO, but that didn't work either.
Do you have a way, how to do that, please?
First of all, just "randomly" connecting both wires is a bad idea.
Below image shows how to do it better for a prototype.
Slave devices are able to pull the IO line low during a read bit or a reset while the TX signal is high.
When used in this configuration, you should not disable RX nor TX. You can use "normal" UART operation.
More information can be found here (maxim integrated tutorial 214 "USING A UART TO IMPLEMENT A 1-WIRE BUS MASTER")
Since you will have a lot of connected slave, you should consider using a dedicated chip:
I use a DS2482S-100 over I2C.
I am new in micro controller programming .I am using embedded C platform for coding. I want to blink LED after every 1 second using timers in LPC 1768. I have option of generating delay using empty "for" loops and crystal frequency for calculation of counter value. But this delay is not precise.
In the given board LPC 1768 is connected to the LEDs through PCA 9532 I2c bus. For controlling LEDs I should use SDA and SCL pins of PCA 9532 .I want to make use of LPC 1768 timers for generating delay of 1 second so that I could blink the LED with 1 second time interval.But problem is that LPC1768 is not directly connected to LED . PCA 9532 is in between them. So can anybody tell me how can I perform it?
It seems like you have to talk to the PCA9532 via I2C.
configure the LPC pins to use I2C
write a simple driver which writes commands over I2C.
configure the PCA9532 via these commands.
PS: If you don't want to write real I2C drivers, you could bit-bang the commands. Be sure to reconfigure the GPIO (SDA) as input to read ACK from chip.
PPS: you find the command structure in the linked datasheet in chapter 7.1 and a sample communication in chapter 8.2.
Hope that's a first help.
I am trying to send/receive data over the serial connection (GPIO UART pins) between a Raspberry Pi 2(raspian wheezy) and an STM32F4 board. I am using the sample code in the link: http://www.raspberry-projects.com/pi/programming-in-c/uart-serial-port/using-the-uart.
It works when I connect the TX and RX pins on the board together. However, when I connect RPI to my laptop by module USB-TTL PL2303 and use hyper terminal to see the result, the received characters are garbage characters. I don't understand why. Is there anything I missed?
Could you give me some advice I could look for, please? Thank you!
Most likely you are using incorrect baud rate. It should be 115200 (115200-8-N-1) (you can use else but then you need to set both endpoints to the same baud). Check the baud rate of the serial connection using stty
stty -F /dev/ttyX
or setserial. In case of baud rate error you can try what authors say:
Try using a slower BAUD rate (or a single 0xFF byte which only has the
start bit low) and see if it works. We had a problem using 115k2 baud
rate where our microcontroller communicating with the RPi could hit
113636baud or 119047baud. 113636baud had the lowest error margin so
we used it and TX from the RPi being received by the microcontroller
worked fine. However when transmitting to the RPi nothing was ever
received. Changing the microcontroller to use 119047baud caused RX to
work.
I am trying to communicate to the Nonin Pulse oximeter device to read the data (Pulse rate and SPO2 level) via Bluetooth. Nonin device supports SPP and HDP profile. I want to communicate through SPP profile. I am able to scan and pair with the device by the sample code available in Bluez.
Please tell me next steps how to send command and read data from the device. I have got struck at this point.
I realize this is a late response, but I recently setup data acquisition from a Nonin PalmSAT 2500A VET unit. I am using the RTC-1000 cable and an RS232 to USB converter.
This is straight from the manual:
"Information from the device, in the real-time mode, is sent in an ASCII serial format at 9600 baud with 9 data bits, 1 start bit, and 1 stop bit. The data are output at a rate of once per second.
NOTE: The 9th data bit is used for odd parity in memory playback mode. In real-time mode, it is always set to the mark condition. Therefore the real-time data may be read as 8 data bits, no parity.
Real-time data may be printed or displayed by devices other than the pulse oximeter. On power up a header is sent identifying the format and the time and date. Thereafter, the data are sent once per second in the following format:
SPO2=XXX HR=YYY
where “XXX” represents the SpO2 value, and “YYY” represents the pulse rate. The SpO2 and pulse rate will be displayed as “---” if there are no data available for the data reading."
Link to manual:
http://www.proactmedical.co.uk/proshop_support_docs/2500aman.pdf
What model oximeter are you working with?
Ist there any possibility to read values from the pins of the COM Port? Any solution in C under Linux is appreciated!
Yes, see for instance this guide.
You use the ioctl() function, to read the various control pins. Data is, of course, best read through the normal read() handling, you don't want to be polling asynchronuous serial data.
I don't think your assumption (expressed in a comment) that the driver must check the pin-states to handle data is correct, normally a serial port is "backed" by an UART and that typically handles the RX/TX pins in hardware.
Am pretty sure , you can't read/write pins of UART.
Even at the hardware level , you have to read/write an entire byte.There is no bit access or read/write pin access.
The Byte is read/written in the Receive/Transmit UART buffer .
In either ways you can't just access the buffer directly , on your behalf the linux driver will do the job. You just have to make use of the driver in your application , to work with the UART , the linux driver for UART provides , standard API's like open(),read(),write(),ioctl() through which you interact the UART device.
If you want to work with drivers , and new to this field , the best place to start will be
this book.
The exact answer to this question depends on the precise hardware in question. I know of a piece of code where I worked, based on receiving the letter 'a' as the indication of bitrate, and it would poll the RX pin to detect the transitions between 0 and 1 to detect the "width" of the bits, and it would then calculate the correct clock-rate for the serial port and configure the serial port to match the bitrate of the other end.
A "PC" type hardware solution will not be able to read the RX/TX pins. In other hardware, it may be possible to do so. Many embedded systems allow various pins to be configured as inputs, outputs or "have a function" (in our case, RX, TX, CTS, RTS, etc) - so for example, you could configure the RX pin to be a input, and thus read the state of it. Of course, the normal serial port drivers will probably set these pins to "have a function" [or expect the boot code running before the kernel is started to have configure it this way]. So you would have to reconfigure the pins in some kernel code of your own, most likely. Beware that this may cause unexpected side-effects with the driver for the actual serial port - it may "get upset" when it tries to do things to the serial port and it's "not working as expected" because it's been "misconfigured".
You can almost certainly read (and/or write) the state of the control pins, such as CTS, RTS via IOCTL calls.