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Message |
jogibaer
Joined: 03 Nov 2011
Posts: 8
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| MRF24J40 Receiver |
 Posted: Tue Nov 15, 2011 8:30 am |
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I am working with the PIC 18F13K22 and the MRF 24J40. My compiler version is 4.114. I want to create a network where I can send data. The transmitter is working fine now. But I can't get the receiver running. I looked it up in the MRF data sheet where the reception is described.
The single steps are:
1. receive RXIF interrupt
2. disable host microcontroller interrupts
3. set RXDECINV =1 (in BBREG1) , disable receiving packets off air
4. read address 0x300
5. read RXFIFO
6. clear RXDECINV
7. Enable host microcontroller interrupts
I translated it like this:
| Code: |
void read_RX_FIFO()
{
int i=0;
SetShortRAMAddress(INTSTAT, 0b00001000);
SetShortRAMAddress(INTCON, 0b00001000);
SetShortRAMAddress(BBREG1, 0b00000100);
SetShortRAMAddress(RXMCR, 0x01);
SetShortRAMAddress(RXFLUSH, 0x00);
for(i=0;i<128;i++)
{
data_RX_FIFO[i]=GetLongRAMAddress(address_RX_FIFO+i);
}
SetShortRAMAddress(BBREG1, 0x00);
SetShortRAMAddress(INTCON, 0b00000000);
}
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After I have called this function in the main loop. I debugged my code and recognized that it stops at this function, when I want to read out RX Fifo. The program stucked in the GetLongRAMAddress function.
| Code: |
int8 GetLongRAMAddress(int16 address)
{
int8 toReturn;
output_low(MRF24J40_CS);
spi_write(((address>>3) & 0b01111111)| 0x80);
spi_write(((address<<5) & 0b11100000)); //stops at this position
toReturn = spi_read(0);
output_high(MRF24J40_CS);
return(toReturn);
}
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I thought that this should be right. Would be glad if anyone could help me. |
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temtronic
Joined: 01 Jul 2010
Posts: 9221
Location: Greensville,Ontario
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| Posted: Tue Nov 15, 2011 8:38 am |
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I don't use that device but have you manually( pen and paper) done the math to confirm that your computed spi_write(address..) is valid ?
Perhaps hard coding a 'good address' will confirm this ??? |
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jogibaer
Joined: 03 Nov 2011
Posts: 8
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| Posted: Tue Nov 15, 2011 3:12 pm |
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I also looked this function up in some other codes, for example the MRF24J40 Radio Driver. I think this should be right, because it is already working with my transmitter.
What do you mean by a 'good address'? |
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jogibaer
Joined: 03 Nov 2011
Posts: 8
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| Posted: Thu Nov 17, 2011 10:43 am |
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| I made some test and found out that the program don't stop at the Get function. I read the received values with my logic analyzer and saw strange and continuously repeating values. I have absolutely no idea what is the problem with this code. I also included in the main loop an if condition. When the data contains my value, one led should flash. otherwise another led should flash. Even if I don't transmit anything I still have a flashing led and get values in the logic analyzer. Is this still a problem of the RX buffer? |
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Douglas Kennedy
Joined: 07 Sep 2003
Posts: 755
Location: Florida
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| Posted: Sat Nov 19, 2011 12:44 pm |
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I can read the received packet data I'm in the middle of this today.
The issue is that absent my unfinished logic of deciphering the header length I'm using fixed values not those obtained from the on air packet. I'm almost there
| Code: |
void read_RX_normal_FIFO(void)
{
unsigned int8 i,frame_size,frame_control;
SetShortRAMAddress(INTSTAT, 0b00001000);
SetShortRAMAddress(INTCON, 0b00001000);
SetShortRAMAddress(BBREG1, 0b00000100);
SetShortRAMAddress(RXMCR, 0x01);
SetShortRAMAddress(RXFLUSH, 0x00);
//// first byte is the frame length
frame_size=GetLongRAMAddress(address_RX_normal_FIFO);
/// next byte is the frame control ex 0xc841
/// we will use it to get the header length
/// Notes sure electronics uses 0xc841 and destination address of0xffff
/// ex 0xc841 0b 11 00 10 000100 0 001
/// |--------| |+++++||--| |++++|
/// c 8 4 1
/// 11 xx 10 xxx#xx x 001
/// long short data
/// source destination
frame_control=GetLongRAMAddress(address_RX_normal_FIFO+1);
for(i=0;i<(HEADER_LENGTH+DATA_LENGTH+2);i++)
{
data_RX_normal_FIFO[i]=GetLongRAMAddress(address_RX_normal_FIFO+i);
}
SetShortRAMAddress(BBREG1, 0x00);
SetShortRAMAddress(INTCON, 0b00000000);
///// transfer payload to RX_DATA
for(i=0;i<DATA_LENGTH;i++)
DATA_RX[i]=data_RX_normal_FIFO[i+(HEADER_LENGTH+4-1)];
}
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jogibaer
Joined: 03 Nov 2011
Posts: 8
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| Posted: Mon Nov 21, 2011 8:07 am |
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First thank you for your code.
I tried to compile it, bur there is not enough for all the variables. You said that you are also working with CCS. Is that right? How can you make a printf output? It is not possible in my version. |
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