I just wanted to start making experience with the DHT22/AM2302 (a temperature and humidity sensor), but I have no idea how to initialize and get the data of it ... I tried to use GpioPin:
gpioController = GpioController.GetDefault();
if(gpioController == null)
{
Debug.WriteLine("GpioController Initialization failed.");
return;
}
sensorPin = gpioController.OpenPin(7); //Exception throws here
sensorPin.SetDriveMode(GpioPinDriveMode.Input);
Debug.WriteLine(sensorPin.Read());
but get the exception: "A resource required for this operation is disabled."
After that I took a look at the library for the unixoids and found this:
https://github.com/technion/lol_dht22/blob/master/dht22.c
But I have no idea how to realize that in VCSharp using Windows 10, anyone an idea or experience?
Thank you very much in advance!
UPDATE:
I got the hint, that there is not GPIO-Pin 7 and this is true, so I re-tried it, but the GPIO-Output seems to be just HIGH or LOW ... So I have to use the I2C or the SPI ... According to this Project, I decided to try it out with SPI: http://microsoft.hackster.io/windowsiot/temperature-sensor-sample and making steps forward ... The difficulty now is to translate the above linked C-Library to the C-Sharp-SDK to receive the right data ...
private async void InitSPI()
{
try
{
var settings = new SpiConnectionSettings(SPI_CHIP_SELECT_LINE);
settings.ClockFrequency = 500000;
settings.Mode = SpiMode.Mode0;
string spiAqs = SpiDevice.GetDeviceSelector(SPI_CONTROLLER_NAME);
var deviceInfo = await DeviceInformation.FindAllAsync(spiAqs);
SpiDisplay = await SpiDevice.FromIdAsync(deviceInfo[0].Id, settings);
}
catch(Exception ex)
{
Debug.WriteLine("SPI Initialization failed: " + ex.Message);
}
}
This works not so well, to be clear: It works just once on starting up the raspberry pi2, then starting / remote debugging the application, but after exiting the application and re-start them, the SPI Initialization fails.
And now Im working on reading the data from the pin and will show some Code in a future update. Any comments, answers and or advices are still welcome.
DHT22 requires very precise timing. Although Raspberry PI/Windows 10 IoT core is extremely fast, since it's an operating system where other things need to happen unless you write some sort of low-level driver (not C#) you won't be able to generate the timings necessary to communicate with a DHT22.
What I do is use a cheap Arduino Mini Pro for about $5 with the sole purpose to generate and send the correct timings between the microcontroller and the Raspberry Pi, then setup some sort of communication channel between the Arduino Mini Pro (I2C, Serial) to pull the data from the Arduino.
Related
Background
I have a small battery powered system running on freeRTOS. I need to periodically run OTA updates, as per any proper internet connected device. The problem is that, being battery powered, the device spends 99.9% of it's life in deep sleep.
When the device is awake, it's possible to post an OTA update from AWS, by publishing to the device's OTA/update topic. From the console, you can only use QOS = 0. But from inside, say a lambda, I believe it's possible to use QOS = 1.
{
"state": {
"desired": {
"ota_url":"https://s3-ap-southeast-2.amazonaws.com/my.awesome.bucket/signed_binary_v21.bin"
}
}
}
Questions
How can I modify this approach to successfully update a device that sleeps for 15 minutes at a time, and wakes for maybe 10 s. During the waking period, it sends a message. Is there some way of leaving the desired OTA/update in the shadow that somehow is included in the response from AWS. I've not managed to figure out how shadows really work. OR can you specify a retry period and time to keep trying perhaps?
Is this approach essentially consistent with the most recent best practice from a security perspective : signed binary, encrypted flash & secure boot etc.
Many thanks.
IDF comes with an OTA example that is pretty straight forward. As suggested in the comments on your question, the example downloads the firmware update, and it will automatically revert to the previous image if the updated version has errors that cause a reset. This is the operative part of the example:
extern const uint8_t server_cert_pem_start[] asm("_binary_ca_cert_pem_start");
extern const uint8_t server_cert_pem_end[] asm("_binary_ca_cert_pem_end");
esp_err_t _ota_http_event_handler(esp_http_client_event_t* evt);
#define FIRMWARE_UPGRADE_URL "https://yourserver.com/somefolder/somefirmware.bin"
void simple_ota_task(void* pvParameter)
{
esp_http_client_config_t config = {
.url = FIRMWARE_UPGRADE_URL,
.cert_pem = (char*)server_cert_pem_start,
.event_handler = _ota_http_event_handler,
};
esp_err_t ret = esp_https_ota(&config);
if (ret == ESP_OK)
ESP_LOGW("ota", "Upgrade success");
else
ESP_LOGE(TAG, "Upgrade failure");
esp_restart();
}
void foo()
{
// after initializing WiFi, create a task to execute OTA:
//
xTaskCreate(&simple_ota_task, "ota_task", 8192, NULL, 5, NULL);
}
// event handler callback referenced above, it has no functional purpose
// just dumps info log output
esp_err_t _ota_http_event_handler(esp_http_client_event_t* evt)
{
switch (evt->event_id) {
case HTTP_EVENT_ERROR:
ESP_LOGD(TAG, "HTTP_EVENT_ERROR");
break;
case HTTP_EVENT_ON_CONNECTED:
ESP_LOGD(TAG, "HTTP_EVENT_ON_CONNECTED");
break;
case HTTP_EVENT_HEADER_SENT:
ESP_LOGD(TAG, "HTTP_EVENT_HEADER_SENT");
break;
case HTTP_EVENT_ON_HEADER:
ESP_LOGD(TAG, "HTTP_EVENT_ON_HEADER, key=%s, value=%s", evt->header_key, evt->header_value);
break;
case HTTP_EVENT_ON_DATA:
ESP_LOGD(TAG, "HTTP_EVENT_ON_DATA, len=%d", evt->data_len);
break;
case HTTP_EVENT_ON_FINISH:
ESP_LOGD(TAG, "HTTP_EVENT_ON_FINISH");
break;
case HTTP_EVENT_DISCONNECTED:
ESP_LOGD(TAG, "HTTP_EVENT_DISCONNECTED");
break;
}
return ESP_OK;
}
To setup embedding the cert, obtain the public key by examining the SSL cert for the site on which the bin file will reside, with a web browser, save it, then convert it to Base64, aka PEM format. (I used some web page.) In my case I created a directory at the same level as the /main directory, called /server_certs, and saved the Base64 conversion in that directory as ca_cert.pem. (That was way too pedantic, wasn't it?)
Then added these lines to CMakeFiles.txt in the /main directory:
# Embed the server root certificate into the final binary
set(COMPONENT_EMBED_TXTFILES ${IDF_PROJECT_PATH}/server_certs/ca_cert.pem)
register_component()
The thing that was unclear to me was how to determine that a newer version is available, if there is a built-in way I couldn't discern it, and did not want to download the update for nothing, ever. So I rolled my own, embedded a version string in the firmware, created a WebAPI entry point on my server that returns the current version (both maintained by hand until I can think of a better way... that I feel like implementing) and call the OTA functionality when the strings don't match. It looks a lot like this:
// The WebAPI returns data in JSON format,
// so if a method returns a string it is quoted.
#define FW_VERSION "\"00.09.015\""
// the HTTP request has just completed, payload stored in recv_buf
//
// tack a null terminator using an index maintained by the HTTP transfer
recv_buf[pos + 1] = 0;
// test for success
if (strncmp(recv_buf, "HTTP/1.1 200 OK", 15) == 0)
{
// find the end of the headers
char *p = strstr(recv_buf, "\r\n\r\n");
if (p)
{
ESP_LOGI("***", "version: %s content %s", FW_VERSION, (p + 4));
if (strcmp((p + 4), FW_VERSION) > 0)
{
// execute OTA task
foo();
}
else
{
// Assumes the new version has run far enough to be
// considered working, commits the update. It doesn't
// hurt anything to call this any number of times.
esp_ota_mark_app_valid_cancel_rollback();
}
}
}
If you're not using the CMake/Ninja build tools, consider checking it out, it's way, way faster than the MingW32-based tool set.
As you have mentioned, you do not fully understand how shadows work, let me explain how using shadows may fit in scenario similar to yours.
Normally, a device that sleeps for long and wakes up for a short duration, usually makes a request to device shadow at wake up. If the shadow contains
{"state": {"desired":{"ota_url": "xxx", "do_ota": true, ...}}},
In this case, device should initiate ota update code inside device.
Further, the approach mentioned here has nothing to do with security and best practices (signed binary, encrypted flash and secure boot). All these three things should be handled by ota update program. Shadows are only used to indicate that there is a ota update available. Using shadow help you avoid making unnecessary GET Request to OTA server, in turn saving precious power and compute resources.
Does anyone know if there is an API to get the current monitor state (on or off) in Windows (XP/Vista/2000/2003)?
All of my searches seem to indicate there is no real way of doing this.
This thread tries to use GetDevicePowerState which according to Microsoft's docs does not work for display devices.
In Vista I can listen to GUID_MONITOR_POWER_ON but I do not seem to get events when the monitor is turned off manually.
In XP I can hook into WM_SYSCOMMAND SC_MONITORPOWER, looking for status 2. This only works for situations where the system triggers the power off.
The WMI Win32_DesktopMonitor class does not seem to help out as well.
Edit: Here is a discussion on comp.os.ms-windows.programmer.win32 indicating there is no reliable way of doing this.
Anyone else have any other ideas?
GetDevicePowerState sometimes works for monitors. If it's present, you can open the \\.\LCD device. Close it immediately after you've finished with it.
Essentially, you're out of luck—there is no reliable way to detect the monitor power state, short of writing a device driver and filtering all of the power IRPs up and down the display driver chain. And that's not very reliable either.
You could hook up a webcam, point it at your screen and do some analysis on the images you receive ;)
Before doing anything based on the monitor state, just remember that users can use a machine with remote desktop of other systems that don't require a monitor connected to the machine - so don't turn off any visualization based on the monitor state.
You can't.
Look like all monitor power capabilities connected to the "power safe mode"
After searching i found here code that connecting between SC_MONITORPOWER message and system values (post number 2)
I use the code to testing if the system values is changing when i am manually switch off the monitor.
int main()
{
for(;monitorOff()!=1;)
Sleep(500);
return 0;
}//main
And the code is never stopped, no matter how long i am switch off my monitor.
There the code of monitorOff function:
int monitorOff()
{
const GUID MonitorClassGuid =
{0x4d36e96e, 0xe325, 0x11ce,
{0xbf, 0xc1, 0x08, 0x00, 0x2b, 0xe1, 0x03, 0x18}};
list<DevData> monitors;
ListDeviceClassData(&MonitorClassGuid, monitors);
list<DevData>::iterator it = monitors.begin(),
it_end = monitors.end();
for (; it != it_end; ++it)
{
const char *off_msg = "";
//it->PowerData.PD_PowerStateMapping
if (it->PowerData.PD_MostRecentPowerState != PowerDeviceD0)
{
return 1;
}
}//for
return 0;
}//monitorOff
Conclusion : when you manually switch of the the monitor, you cant catch it by windows (if there is no unusual driver interface for this), because all windows capabilities is connected to "power safe mode".
In Windows XP or later you can use the IMSVidDevice Interface.
See
http://msdn.microsoft.com/en-us/library/dd376775(VS.85).aspx
(not sure if this works in Sever 2003)
With Delphi code, you can detect invalid monitor geomerty while standby in progress:
i := 0
('Monitor'+IntToStr(i)+': '+IntToStr(Screen.Monitors[i].BoundsRect.Left)+', '+
IntToStr(Screen.Monitors[i].BoundsRect.Top)+', '+
IntToStr(Screen.Monitors[i].BoundsRect.Right)+', '+
IntToStr(Screen.Monitors[i].BoundsRect.Bottom))
Results:
Monitor geometry before standby:
Monitor0: 0, 0, 1600, 900
Monitor geometry while standby in Deplhi7:
Monitor0: 1637792, 4210405, 31266576, 1637696
Monitor geometry while standby in DeplhiXE:
Monitor0: 4211194, 40, 1637668, 1637693
This is a really old post but if it can help someone, I have found a solution to detect a screen being available or not : the Connecting and Configuring Displays (CCD) API of Windows.
It's part of User32.ddl and the interesting functions are GetDisplayConfigBufferSizes and QueryDisplayConfig. It give us all informations that can be viewed in the Configuration Panel of windows.
In particular the PathInfo contains a TargetInfo property that have a targetAvailable flag. This flag seems to be correctly updated on all the configurations I have tried so far.
This allow you to know the state of every screens connected to the PC and set their configurations.
Here a CCD wrapper for .Net
If your monitor has some sort of built-in USB hub, you could try and use that to detect if the monitor is off/on.
This will of course only work if the USB hub doesn't stay connected when the monitor is consider "off".
Is it possible to emulate steering wheel? I mean say to windows like I'm pressing 30% of left button? Or do I need to write some driver which will communicate with my application? So that windows will think that it is a real device.
If I need driver, then what commands I need to send to windows to do right things, maybe I can send them directly from my application.
I have small experience writing application which communicate with card reader using virtual com port, but there was real device :/
Maybe I can use some real steering wheel driver, install it in windows and then send command to some com port to make windows think that it's real device?
Please help, or at least show direction where I can find some information.
Found a solution on http://vjoystick.sourceforge.net/site/. Now I have written the server and the client on my phone and started testing, but it's working somehow slow. I open socket and send from phone 3-5 bytes, but server reads 3-4 messages. Sample("x-100;x-4;x45;")
TcpClient tcpClient = (TcpClient)client;
NetworkStream clientStream = tcpClient.GetStream();
byte[] message = new byte[1000];
int bytesRead;
while (ThreadsRun) {
bytesRead = 0;
try {
bytesRead = clientStream.Read(message, 0, 1000);
var stringMsg = "";
for (int i = 0; i < bytesRead; i++) {
stringMsg += (char)message[i];
}
queue.Enqueue(stringMsg);//conqurentqueue
} catch {
break;
}
Thread.Sleep(1);
}
tcpClient.Close();
Code is very simple and should be fast, ping from phone is 40ms sending 56 bytes.
What is wrong here or is there another faster way to send small amount of data very frequently?
I'm working with the NetworkUtils.java class created by Sameer Nafdey in his blog post regarding accuiring a network connection within a Blackberry Application. However I recently noticed that my application was using the cell network even when a WiFi connection was available. I realized this was the case when we tested the application on a Torch with no SIM card and the app failed. After some debugging I found that:
if (WLANInfo.getWLANState() == WLANInfo.WLAN_STATE_CONNECTED){...}
was returning false despite the fact that the WiFi network was setup correctly (I was able to use web browser to visit Google). We had to return the Torch but while debugging the app in the simulator I noticed that if WiFi was on but the Data Network was turned off then this call would work correctly. However I would then get an exception (java.io.ioexception: Radio is off) when executing this block:
httpConnector = (HttpConnection)Connector.open(URL);
httpConnector.setRequestMethod(HttpConnection.GET);
httpConnector.setRequestProperty("Content-Type", "text/plain; charset=UTF-8");
in = httpConnector.openInputStream();
I've seen a lot of issues related to the Torch's WiFi connectivity problems but I'm currently concerned that this behavior may also be affecting other models. Anyone seen anything like this or have an idea of how to fix it?
You could try:
if( RadioInfo.areWAFsSupported( RadioInfo.WAF_WLAN )
&&
( RadioInfo.getActiveWAFs() & RadioInfo.WAF_WLAN ) != 0
&&
CoverageInfo.isCoverageSufficient( 1 , RadioInfo.WAF_WLAN, false) )
{ ... }
It's been working so far, on Blackberry OS 6.0 (Torch 9800). Tested on device and sim.
I am using jxa-1.0 to create Instant Messaging application in blackberry while running the application i m getting exception like "java.io.IOException: Stream closed".Could you please tell me how to fix this?? or if u have prior experience with Jxa-1.0 pls share your ideas about how to use this one.
If you want to avoid this error on simulators, you should read the InputStream one byte at a time, try this code (consider NOT using this method when working with a real device, since performance will be affected):
InputStream is = httpConnection.openInputStream();
int data = -1;
ByteArrayOutputStream bos = new ByteArrayOutputStream();
data = is.read();
bos.write(data);
while (data >= 0) {
try {
data = is.read();
} catch (Exception e) {
// Replace exception with "-1". This is to handle anomalous End-of-Stream in OS 5.
data = -1;
}
bos.write(data);
}
byte[] byteArray = bos.toByteArray();
If you are seeing this error message in a simulator, don't be surprised. I see I/O errors like this quite often in simulators, especially over Direct TCP or Wi-Fi connections. Some of the newer 5.0 simulators seem to be more problematic than older ones.
If you haven't yet, try it on a real device and it will probably be better.