shows the flow used to read a single word of data from the parallel port.
•
8-bit data stream
, discards the upper 8-bits of the first read from the port and treats the
lower 8-bits masked with GPIO31 in bit position 7 and GPIO30 in bit position 6 as the least-significant byte
(LSB) of the word to be fetched. The routine will then perform a second read to fetch the most-significant byte
(MSB). It then combines the MSB and LSB into a single 16-bit value to be passed back to the calling routine.
(AIO6 = 0)
Signal host that 28x is ready
Parallel_GetWordData
8 bit
(AIO12 = 0)
?
Data
ready
Yes
from GPIO[31,30,5:0]
Read word of data
(AIO6 = 1)
28x ack read complete
(AIO12 = 1)
ack
Host
No
?
A
ack
Host
(AIO12 = 1)
28x ack read complete
(AIO6 = 1)
?
ready
Data
(AIO12 = 0)
Signal host that 28x
(AIO6 = 0)
is ready to read MSB
?
A
Read GPIO[15:0]
with GPIO[31:30] masked
into GPIO[7:6] for LSB of data,
Discard GPIO[15:8],
repeat for MSB of data.
Return WordData
WordData = MSB:LSB
No
No
No
Yes
Yes
Yes
Figure 2-19. 8-Bit Parallel GetWord Function
Boot ROM
226
TMS320x2806x Microcontrollers
SPRUH18I – JANUARY 2011 – REVISED JUNE 2022
Copyright © 2022 Texas Instruments Incorporated
Summary of Contents for TMS320 2806 Series
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