MRF24J40 Datasheet, PDF (19/66 Pages) Microchip Technology – IEEE 802.15.4™ 2.4 GHz RF Transceiver

4.3.2
WRITING LONG ADDRESS
REGISTERS
The long address space is accessed by sending a ‘1 ‘
as the first bit of the SPI transfer. The following 10 bits
are the address of the target register. The final bit is a
‘1 ‘ to indicate that the command is a write. On the next
clock edge of SCK, the Most Significant bit of the
register will shift out, followed by the rest of the bits.
MRF24J40
4.4 Buffer Interface
The receive and transmit buffers in the MRF24J40 are
located in the long RAM address space. These buffers
are accessed using the same process as accessing the
long RAM control addresses. The received buffer is
read-only and should not be written to. The use of these
buffers is described in Section 7.0 “Transmitting and
Receiving Packets”.
FIGURE 4-6:
LONG ADDRESS WRITE
CS
SCK
SDI
SDO
1 A9 A8 A7 A6 A5 A4 A3 A2 A1 A0 1
X
D7 D6 D5 D4 D3 D2 D1 D0
X
EXAMPLE 4-4: LONG ADDRESS WRITE EXAMPLE
void SetLongRAMAddress(WORD address, BYTE value)
{
CSn = 0;
SPIPut((((BYTE)(address>>3))&0b01111111)|0x80);
SPIPut((((BYTE)(address<<5))&0b11100000)|0x10);
SPIPut(value);
CSn = 1;
}
© 2006 Microchip Technology Inc.
Advance Information
DS39776A-page 17