i try to read and write something in CoreBluetooth
So my device(peripheral) send me the lenght of a array
and the array as one.
I read the value with this method
(void)readValueForCharacteristic:(CBCharacteristic *)characteristic;
when i get the answer from the peripheral the
(void)peripheral:(CBPeripheral *)peripheral didUpdateValueForCharacteristic:(CBCharacteristic *)characteristic error:(NSError *)error;
is calling
When i read one value it is not a problem
char arrayLength;
charakteristik.value getBytes:&arrayLength lenght:SERVICE_ARRAYLENGTH_LEN]
self.MyArrayLenght=(float)arrayLength;-
But when i get the array from the Peripheral i dont know how to read them
charakteristik.value is NSData
when i trying to
NSArray *array = [NSKeyedUnarchiver unarchiveObjectWithData:charakteristik.value]
i got error
Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '[NSKeyedUnarchiver initForReadingWithData:]: incomprehensible archive (0x4e, 0x49, 0x42, 0x41, 0x72, 0x63, 0x68, 0x69)'
The hex (0x4e, 0x49, 0x42, 0x41, 0x72, 0x63, 0x68, 0x69.......) are the data what i want to read and later show
How can i read the NSData? Or How i can convert the NSData to NSArray?
Edit:
Problem solved
I am afraid that the unarchived NSData object from the peripheral is incomplete. CoreBluetooth limits maximum size of a characteristic could update each time, which is set by the central device. The exceeded part would be truncated while transferring. Probably the size of your array exceeds the size limitation, thus the central device did not receive the compete one, which results in exception.
The maximum length limitation varies from device to device, you can get the size limitation from the maximumUpdateValueLength property of the CBCentral object given by the CBPeipheralManagerDelegate methods:
- (void)peripheralManager:(CBPeripheralManager *)peripheral central:(CBCentral *)central didSubscribeToCharacteristic:(CBCharacteristic *)characteristic
- (void)peripheralManager:(CBPeripheralManager *)peripheral didReceiveReadRequest:(CBATTRequest *)request
- (void)peripheralManager:(CBPeripheralManager *)peripheral didReceiveWriteRequests:(NSArray *)requests
or any other methods that offer a CBCentral object.
If you want to send over-sized data, you should segment the data into pieces and send them through a couple of times. On the central device, you could rebuild the original data object by combining the pieces together. Apple provides a sample code to illustrate how to send over-sized data. BTLE Central Peripheral Transfer
Probably would have answered your question by now.
Just in case: you can read the NSData content with the method:
char *data = [NSData data];
The length of the data is retrieved with
[NSData length];
To check if it contains your data you can simply do something like:
strncmp(blah, [NSDataObject data], [NSDataObject length]);
Having said that, you can define which service you want to discover and only that one. You can then restrict even further to only listen to the particular characteristic you're interested with in
- (void)peripheral:(CBPeripheral *)peripheral didDiscoverServices:(NSError *)error
call
[peripheral discoverCharacteristics:[NSArray arrayWithObject:[CBUUID UUIDWithString:#"ABCD"]] forService:service];
Hope this help
Related
I am trying to talk to the XBOX ONE Controller via the Microsoft HID API without using XINPUT. I'm currently able to control all the rumble motors (including the force feedback triggers) by sending the packet using HidD_SetOutputReport(HANDLE, VOID*, ULONG). But I'm stuck reading the button values using HidD_GetInputReport(HANDLE, VOID*, ULONG) or ReadFile() / ReadFileEx() with and without the HANDLE being created with FILE_FLAG_OVERLAPPED and using OVERLAPPED and Windows Events.
I have already reverse engineered the USB URB protocol with the help of the following article https://github.com/quantus/xbox-one-controller-protocol. The main goal is to overcome the XINPUT overhead and writing a flexible framework so that I can integrate other gamepads as well.
That is what I accomplished:
I have connected the gamepad via USB with my computer (So that I can read all the USB Packages sent and received from the device)
I have found the controller’s path using SetupDiGetClassDevs(...), SetupDiEnumDeviceInfo(...), SetupDiEnumDeviceInterfaces(...) and SetupDiGetDeviceInterfaceDetail(...)
I have created a handle to the device using HANDLE gamePad = CreateFile(path, GENERIC_READ | GENERIC_WRITE, FILE_SHARE_READ | FILE_SHARE_WRITE, NULL, OPEN_EXISTING, FILE_FLAG_OVERLAPPED, NULL)
Using HidP_GetCaps(HANDLE, HIDP_CAPS*) doesn’t seem to return valid data since it reports a OutputReportByteLength of 0 but I am able to send Output reports of size 5 (Turn ON) and 9 (Set rumble motors)
All in and outcoming data (At least buttons and Rumble motors) seem to follow the following pattern
byte 0: Package type
byte 1: was always 0x00
byte 2: Package number (always incrementing every package)
byte 3: Size of following data
byte 4+: <Data>
With that information i was able to let the motors and triggers rumble as I desire
For example: Two of my output rumble packets look like this (Using the pulse length to dirty turn on and off the motors):
This turns on and of all motors with the rumble motors speed at 0xFF and the triggers at speed 0xF0. This is how I did it:
struct RumbleContinous{
BYTE mode;
BYTE mask; // Motor Mask 0b 0 0 0 0 LT RT L R
BYTE lTForce;
BYTE rTForce;
BYTE lForce;
BYTE rForce;
BYTE pulseLength;
BYTE offTime;
BYTE terminator; // Terminator / Dummy / ?? (XINPUT sends that as 0xEB!) / Changing seems to not make any changes
};
RumbleContinous rc = {0x00, 0x0F, 0xF0, 0xF0, 0xFF, 0xFF, 0xFF 0x00, 0xEB};
HidD_SetOutputReport(gamePad, (PVOID)&rc, sizeof(RumbleContinous ));
Now to my problem
Looking at the input packages from the controller it looks like you need to create a buffer of size 0x0E = 14, ZeroMemory it (or just write the first byte to 0 like MSDN is suggesting) and just call HidD_GetInputReport(HANDLE, buffer, 14)
So what I did was calling HidD_FlushQueue() to make sure the next package is the input package. Then I insert a little delay so that I am able to change some controller values. After that I tried reading into a BYTE array with HidD_GetInputReport(HANDLE, cmd_in, 14) but the function always failed with GetLastError() == 0x00000057 // ERROR_INVALID_PARAMETER
Since HID is able to filter packages it may be required to allocate a buffer one byte larger than expected and pass the required report id to the buffer at location 0. This is what I did:
BYTE cmd_in[15];
ZeroMemory(cmd_in, 15);
cmd_in[0] = 0x20;
HidD_GetInputReport(gamePad, cmd_in, 15);
Still no success. Since the HidP_GetCaps(...) function reported an input report of 16 (But I don't trust this since it already fooled me with output report size of 0) I tried sweeping over many buffer sizes:
BYTE cmd_in[30];
for (UINT bs = 0; bs < 30; bs++) {
ZeroMemory(cmd_in, 30);
HidD_FlushQueue(gamePad); // Flushing works
Sleep(500);
if (HidD_GetInputReport(gamePad, cmd_in, bs)) {
// Output result (ommited)
}
else {
// Print error (ommited)
}
}
and
BYTE cmd_in[30];
for (UINT bs = 0; bs < 30; bs++) {
ZeroMemory(cmd_in, 30);
cmd_in[0] = 0x20;
HidD_FlushQueue(gamePad); // Flushing works
Sleep(500);
if (HidD_GetInputReport(gamePad, cmd_in, bs)) {
// Output result (ommited)
}
else {
// Print error (ommited)
}
}
Still no success. According to the special required output format and the wrong HidP_GetCaps(...) readings i suspect that the XBOX ONE Gamepad Driver requires a special header already beeing in the input buffer (As far as I know HidD_GetInputReport(...) just calls the User / Kernel Mode Driver call back; So the driver is free to perform checks and reject all data being send to it)
Maybe anyone out there does know how to call HidD_GetInputReport(...) for the XBOX One controller
I know that it is possible to retrieve that input data since the SimpleHIDWrite is able to see the button states. Even through the format is totally different (The two triggers for example are combined in one byte. In the USB Packed each trigger has its own byte):
I should also mention that the HIDWrite sees the data without the press of any button! Looking at the log from the SimpleHIDWrite it looked like it is reading RD from 00 15 bytes of data, having a 16-byte array and element 0 at 00 (Didn't work in my application). Or does it just dump all data coming in. If yes how is this possible? That would be an option for me too!
I looked at what XINPUT is doing when executing the following code:
XINPUT_STATE s;
XInputGetState(0, &s);
It turned out that XINPUT is doing the same stuff I did until it comes to reading the data from the controler. Insteal of HidD_GetInputReport(...) XINPUT is calling DeviceIoControl(...). So what I did was a fast google serch "DeviceIoControl xbox" and tada here it is without the need to to figure out the memory layout on my own: Getting xbox controller input without xinput
Edit: Using DeviceIoControl(...) works even if the gamepad is connected via bluetooth while HidD_SetOutputReport(...) does not work when the gamepad is connected via bluetooth. I rember reading something that DeviceIoControl(...) via bluetooth requires an addition parameter to be present in the output buffer. But I'm currently trying to figure out a way to controle the rumble motors via DeviceIoControl(...). If you have any sugestions feel free to comment! The article in the link above only activates the two rumble motors but not the triggers!
Edit 2: I tried sweeping over DeviceIoControl(HANDLE, j, CHAR*, i, NULL, 0, DWORD*, NULL) from j 0x0 to 0xFFFFFFFF and i 0x1 to 0x3F. Well it worked... at first... but after a few values of j I got a Blue-Screen: WDF_Violation (At least I know how to crash a computer ;) )
Working on a SPI communication bus between an array of SAMD MCUs.
I have an incoming packet which is something like { 0x00, 0xFF, 0x00, 0xFF }.
The receiver chip performs CRC16 check on the incoming packet.
Since I am expecting the exact same packet every time, I want to have zero CRC checksum when the packet is valid and not zero checksum when there is a transfer error.
I know that I can add the calculated CRC16 to the end of the packet when sending it and on the receiver side the CRC check will output 0, but in this case it is impossible to add a CRC16 checksum to the packet since the packet is constructed by multiple sender chips on the SPI line and each chip only fills its own two bytes from the entire packet.
I need to load an initial CRC checksum on the receiver side, so after the incoming packet is checked, the resulting CRC equals to zero (if packet is intact).
The answer here on SO is actually what I am looking for, but it is for CRC32 format and I don't actually understand the principle of the code, so I can't rewrite if for CRC16 format.
Any help would be greatly appreciated!
Regards,
Niko
The solution is simply to use a look-up table based CRC. If you can't append the checksum (aka the Frame Check Sequence, FCS) to the package, then do the table look-up first and then simply compare that one against the expected sequence for your fixed data.
Please note that "CRC 16" could mean anything, there are multiple versions and (non)standards. The most common one is perhaps the one called "CRC-16-CCITT" with 1021h poly and initial value FFFFh, but even for that one there's multiple algorithms out there - some are correct, some are broken. Your biggest challenge will be to find a trustworthy CRC algorithm.
However, I actually think SAMD specifically uses hardware-generated CRC-16-CCITT on-chip, for DMA purposes. Since this is SPI, it should be DMA-able, so perhaps investigate if you can use that one somehow.
I found a solution, thanks to the advice of Bastian Molkenthin, who did this great online CRC calculator.
He advised trying a brute force calculation of all the 2^16 values of a CRC16 initial value. Indeed, after a few lines of code and few microseconds later the SAMD51 found an initial value, which matches a zero CRC value for the given buffer.
I have a device that I am communicating with by sending and receiving a particular binary packet structure. The device has a somewhat well defined API, but there are over 100 possible message types that it can return. What is a good design to use to handle the processing of these different message types?
Here is an example in pseudocode, I am ignoring framing, and checksum bytes to make it clearer.
// I receive this message, where 0x00 indicates the device status,
//and each other byte is a particular error or status
message = [0x00, 0x01, 0x01, 0x04]
// The next message I receive, where 0x10 indicates system time,
// and the rest of the fields are the integer clock seconds of the device.
message = [0x10, 0x00, 0x32, 0xFF, 0x8E]
// 100 other message types....
As you can see, each message I receive needs to be processed slightly different, has different meanings. I originally was going to use a gigantic switch statement case 0x00: process_errors() case 0x10: process_time() but I was curious if there a better design that I could use to increase flexibility of adding new message types, better useability, etc.
You can try using TLV (Tag Length Value) implementation. It is good for processing stream of data.
Tag - This will be a byte of data(as per your example) which identifies the type of message that follows. For this to be utilized, you should before hand be aware of which message type has how many data. For instance, in case of 0x00 (device status) you should now beforehand that the next 3 bytes are the data.
Length - The length of data bytes
Value - The actual data
Here is what you can do:
1) Prepare a map of the Tag and Length of different messages that your system supports.
2) Receive bytes of data continuously.
3) Read the 1st byte (this will be the tag) and determine what type of message it is. In your case this will give you 0x00, 0x10 etc.
4) Refer to your map of tag and length information. You will determine how many bytes of data you need to read further.
5) Once you read the data portion, your receiver should be ready to receive next message (ready to read next tag)
This is all about reading the messages. Once you have the message and its data with you, you can use it as you like. For instance, in addition to the length of message corresponding to a Tag, you can register a function also. This will let you call a particular function along with the parameters required by it.
Device Status
Data Tag = 00
Data Length = 03
Data Value = 01 01 04
System time
Data Tag = 10
Data Length = 04
Data Value = 00 32 FF 8E
I have some problems with a project I'm doing. Basically I'm just using memcpy the wrong way. I know the theroy of pointer/arrays/references and should know how to do that, nevertheless I've spend two days now without any progress. I'll try to give a short code overview and maybe someone sees a fault! I would be very thankful.
The Setup: I'm using an ATSAM3x Microcontroller together with a uC for signal aquisition. I receive the data over SPI.
I have an Interrupt receiving the data whenever the uC has data available. The data is then stored in a buffer (int32_t buffer[1024 or 2048]). There is a counter that counts from 0 to the buffer size-1 and determines the place where the data point is stored. Currently I receive a test signal that is internally generated by the uC
//ch1: receive 24 bit data in 8 bit chunks -> store in an int32_t
ch1=ch1|(SPI.transfer(PIN_CS, 0x00, SPI_CONTINUE)<<24)>>8;
ch1=ch1|(SPI.transfer(PIN_CS, 0x00, SPI_CONTINUE)<<16)>>8;
ch1=ch1|(SPI.transfer(PIN_CS, 0x00, SPI_CONTINUE)<<8)>>8;
if(Not Important){
_ch1Buffer[_ch1SampleCount] = ch1;
_ch1SampleCount++;
if(_ch1SampleCount>SAMPLE_BUFFER_SIZE-1) _ch1SampleCount=0;
}
This ISR is active all the time. Since I need raw data for signal processing and the buffer is changed by the ISR whenever a new data point is available, i want to copy parts of the buffer into a temporary "storage".
To do so, I have another, global counter wich is incremented within the ISR. In the mainloop, whenever the counter reaches a certain size, i call a method get some of the buffer data (about 30 samples).
The method aquires the current position in the buffer:
'int ch1Pos = _ch1SampleCount;'
and then, depending on that position I try to use memcpy to get my samples. Depending on the position in the buffer, there has to be a "wrap-around" to get the full set of samples:
if(ch1Pos>=(RAW_BLOCK_SIZE-1)){
memcpy(&ch1[0],&_ch1Buffer[ch1Pos-(RAW_BLOCK_SIZE-1)] , RAW_BLOCK_SIZE*sizeof(int32_t));
}else{
memcpy(&ch1[RAW_BLOCK_SIZE-1 - ch1Pos],&_ch1Buffer[0],(ch1Pos)*sizeof(int32_t));
memcpy(&ch1[0],&_ch1Buffer[SAMPLE_BUFFER_SIZE-1-(RAW_BLOCK_SIZE- ch1Pos)],(RAW_BLOCK_SIZE-ch1Pos)*sizeof(int32_t));
}
_ch1Buffer is the buffer containing the raw data
SAMPLE_BUFFER_SIZE is the size of that buffer
ch1 is the array wich is supposed to hold the set of samples
RAW_BLOCK_SIZE is the size of that array
ch1Pos is the position of the last data point written to the buffer from the ISR at the time where this method is called
Technically I'm aware of the requirements, but apparently thats not enough ;-).
I know, that the data received by the SPI interface is "correct". The problem is, that this is not the case for the extracted samples. There are a lot of spikes in the data that indicate that I've been reading something I wasn't supposed to read. I've changed the memcpy commands that often, that I completly lost the overview. The code sample above is one version of many's, and while you're reading this I'm sure I've changed everything again.
I would appreciate every hint!
Thanks & Greetings!
EDIT
I've written down everything (again) on a sheet of paper and tested some constellations. This is the updated Code for the memcpy part:
if(ch1Pos>=(RAW_BLOCK_SIZE-1)){
memcpy(&ch1[0],&_ch1Buffer[ch1Pos-(RAW_BLOCK_SIZE-1)] , RAW_BLOCK_SIZE*sizeof(int32_t));
}else{
memcpy(&ch1[RAW_BLOCK_SIZE-1-ch1Pos],&_ch1Buffer[0],(ch1Pos+1)*sizeof(int32_t));
memcpy(&ch1[0],&_ch1Buffer[SAMPLE_BUFFER_SIZE-(RAW_BLOCK_SIZE-1-ch1Pos)],(RAW_BLOCK_SIZE-1-ch1Pos)*sizeof(int32_t));
}
}
This already made it a lot better. From all the changes, everything kinda got messed up. Now there is just one Error there. There is a periodical spike. I'll try to get more information, but I think it is a wrong access while wrapping around.
I've changed the if(_ch1SampleCount>SAMPLE_BUFFER_SIZE-1) _ch1SampleCount=0; to if(_ch1SampleCount>=SAMPLE_BUFFER_SIZE) _ch1SampleCount=0;.
EDIT II
To answer the Questions of #David Schwartz :
SPI.transfer returns a single byte
The buffer is initialised once at startup: memset(_ch1Buffer,0,sizeof(int32_t)*SAMPLE_BUFFER_SIZE);
EDIT III
Sorry for the frequent updates, the comment section is getting too big.
I managed to get rid of a bunch of zero values at the beginning of the stream by decreasing ch1Pos: 'int ch1Pos = _ch1SampleCount;' Now there is just one periodic "spike" (wrong value). It must be something with the splitted memcpy command. I'll continue looking. If anyone has an idea ... :-)
I'm trying to write some code to read from an Isochronous pipe using LibUsbK in Win32. I have successfully initialised the device into the correct state to send and receive Isochronous data and I can see data being sent over the USB in my hardware USB analyser, but the buffers I am receiving are always unfilled even though the analyser shows that there was data in the packets sent to the PC.
I'm new to LibUsbK and using Isochronous transfers though I'm not new to USB in general but I've been really struggling with this.
The code I'm using to read from the device is something like this...
UsbK_SelectInterface(usbHandle,1,0);
UsbK_SetAltInterface(usbHandle,1,0,1);
IsoK_Init(&isoCtx, ISO_PACKETS_PER_XFER, 0);
IsoK_SetPackets(isoCtx, ISO_PACKET_SIZE); // Size of each individual packet
OvlK_Init(&ovlPool, usbHandle, 4, 0);
OvlK_ResetPipe(usbHandle, 0x83);
OclK_Acquire(&ovlkHandle, ovlPool);
UsbK_IsoReadPipe(usbHandle, 0x83, inBuffer, sizeof(inBuffer), ovlkHandle, isoCtx);
while(!finished)
{
if(OvlK_IsComplete(ovlkHandle)
{
fwrite(inBuffer, sizeof(inBuffer), 1, outFile);
memset(inBuffer,0xcc,sizeof(inBuffer));
OvlK_ReUse(ovlkHandle);
UsbK_IsoReadPipe(usbHandle, 0x83, inBuffer, sizeof(inBuffer), ovlkHandle, isoCtx);
{
}
If I put a breakpoint at the fwrite line then the inBuffer is always full of 0xCC - ie, not having been filled by the iso read.
I've checked all the error return values from the UsbK/OvlK function calls and they are all as they should be. I've checked my buffers are sufficiently big to receive the data.
I use very similar code to write to the ISO out pipe on endpoint 0x02 and that works perfectly, the only difference really between the code above and my write code is that the fwrite/memset commands are replaced with a call to a "fillbuffer" function that populates my outBuffer before calling UsbK_IsoWritePipe function.
I tried looking through any examples I could find in the samples and also online but struggled to understand/get them to work with my particular device.
Any suggestions or help greatly appreciated.
So it appears that the above code did work and I was being mislead by the fact that the debugger was interrupting the flow of things - I keep forgetting that trying to debug real time stuff can introduce it's own issues.
The first issue was that stepping through the code in the debugger was causing issues with the low level libusbk code capturing the usb packets and filling my buffers correctly - once I let it run full speed and found other ways to test the buffers I did actually find there was some data in there.
The second problem I had was that quite often the buffer was starting to be filled part way through only (and not always right from the start) so when I examined the data I was only printing the first part of the buffer to the console and so all I saw was 0xCC and I was therefore assuming it hadn't worked.
Once I realised that there was actually some data later in the buffer I just started looking through the buffer in packet sized chuncks, if the packet was completely contained of 0xCC I would skip it and move on, but if any of it was not 0xCC then I would treat it as a valid packet - this worked perfectly and I was successfully receiving all the data. I'm sure there's a more "proper" way of doing this, but it works for me now.