rpc2a-000-dil Radiometrix Ltd, rpc2a-000-dil Datasheet - Page 7

• Manufacturer Part Number: rpc2a-000-dil
• Description: Uhf Radio Packet Controller
• Manufacturer: Radiometrix Ltd

figure 7: TX download timing diagram
The sequence for a byte transfer from the Host to the RPC2A (i.e. TX download) is asynchronous and
proceeds as follows:
1. HOST asserts TX Request line low to initiate transfer
2. Wait for RPC2A to pull TX Accept low (i.e. request is accepted)
3. Set data lines to output and place LS nibble on the data lines
4. Negate TX Request (set to 1) to tell RPC2A that data is present.
5. Wait for RPC2A to negate TX Accept (i.e. data has been accepted)
Repeat steps 1-5 with MS nibble.
Notes:
Radiometrix Ltd, RPC2A
The data bus must not be set to output until step 3. i.e. after the RPC2A has accepted the request.
The bus may be left as an output until the entire packet has been transferred to the RPC2A, it
should then be set back to input (default state).
The RPC2A's normal response time to the initial TX Request may be up to 1ms, thereafter, for the
duration of the packet, the response will be fast.
The RPC2A will ignore a TX Request from the Host while it is receiving a packet from the radio. If
the incoming packet fails it's error check the RPC2A will respond to the TX Request as normal, i.e.
the TX Accept from the RPC2A will be delayed until the incoming packet has finished. If a valid
packet is received this must be uploaded to the Host before the RPC2A can respond to the Host’s TX
Request. Thus an RX Request will be signalled to the Host and not the expected TX Accept and the
Host must upload the incoming packet before the TX packet can be downloaded. The TX Request
should be left asserted (low) during the upload. The RPC2A will respond as normal after the upload
is completed.
For the above reason it is often easier to use RX Request to trigger a HOST interrupt and upload the
RPC2A to the HOST under interrupt control.
See Appendix B and C. for example RPC2A driver subroutines.
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