2.1.2 R
EAD A BYTE FROM THE
FRPC2
The sequence for a byte transfer from the FRPC2 to the HOST (i.e. RX upload) is asynchronous and
proceeds as follows :-
1.
2.
3.
4.
FRPC2 will assert RX Request line low to initiate transfer
Host pulls RX Accept low (i.e. request is accepted by the host)
FRPC2 will turn on it's bus drivers, place LS nibble onto data lines
and negate RX Request (set to 1)
Host reads the data and negates RX Accept (i.e. data has been accepted)
Repeat steps 1-4 with MS nibble.
figure 8: RX upload timing diagram
Notes:
•
The FRPC2 will turn off it's data bus drivers after the entire packet has been uploaded to the HOST.
•
See Appendix B and C. for example FRPC2 driver subroutines.
2.2 H
OST
<> FRPC2 P
ACKET
F
ORMAT
2.2.1 T
HE
C
ONTROL
B
YTE
The first byte of a FRPC2 <> HOST packet transfer is always the
C
ONTROL
B
YTE
. This byte is used to
control the transfer and contains information about the type of packet, number of bytes to be
transferred, memory address, read/write bit etc. Bit 7 of the control byte is the Packet Type flag, PT, it
determines the class of transfer and the interpretation of the other bits in the control byte.
Radiometrix Ltd, FRPC2
page
8
RADIOMETRIX [ RADIOMETRIX LTD ]
