mirror of
git://projects.qi-hardware.com/ben-blinkenlights.git
synced 2024-11-23 23:00:38 +02:00
175 lines
4.6 KiB
Plaintext
175 lines
4.6 KiB
Plaintext
UBB pattern generator
|
|
=====================
|
|
|
|
ubb-patgen uses the MMC controller in the Ben Nanonote to send a
|
|
digital pattern on the DATx lines of UBB. All four DATx lines can
|
|
be used. The maximum output rate is 56 MHz, the maximum pattern
|
|
size is 8128 nibbles.
|
|
|
|
ubb-patgen can also output a clock of arbitrary duration on the
|
|
CLK signal.
|
|
|
|
The frequencies available for the pattern and the clock signal
|
|
range from 41 kHz to 56 MHz. A map can be found here:
|
|
http://downloads.qi-hardware.com/people/werner/ubb/ben-mmc-clk.png
|
|
|
|
|
|
Frequency list
|
|
--------------
|
|
|
|
# ubb-patgen
|
|
|
|
shows the available frequencies in ascending order and the
|
|
corresponding MMC clock divider and bus clock tap settings.
|
|
|
|
# ubb-patgen -q
|
|
|
|
does the same but shows only the frequencies (in Hz) as
|
|
floating-point numbers.
|
|
|
|
|
|
Frequency selection
|
|
-------------------
|
|
|
|
# ubb-patgen -f 17000000
|
|
# ubb-patgen -f 17M
|
|
# ubb-patgen -f 17MHz
|
|
|
|
all look for the available frequency closest to 17 MHz and print
|
|
its value in Hz.
|
|
|
|
Appending a + limits the search to frequencies greater than or
|
|
equal to the specified value. Similarly, - searches for
|
|
frequencies that don't exceed the specified value. Examples:
|
|
|
|
# ubb-patgen -f 10MHz
|
|
9882352.941176
|
|
# ubb-patgen -f 10MHz+
|
|
10500000.000000
|
|
|
|
# ubb-patgen -f 15M
|
|
15272727.272727
|
|
# ubb-patgen -f 15M-
|
|
14000000.000000
|
|
|
|
Note that this form of invocation only searches the frequency
|
|
table but does not produce any output on UBB.
|
|
|
|
ubb-patgen warns if the selected frequency does not match the
|
|
requested frequency, e.g.,
|
|
|
|
# ubb-patgen -f 100kHz
|
|
bus clk = 100.962 kHz (+0.96%)
|
|
|
|
This warning can be suppressed with the option -q.
|
|
|
|
The frequency can also be specified as the cycle time with the
|
|
option -i:
|
|
|
|
# ubb-patgen -i 10us
|
|
|
|
The meaning of an appended + or - changes here, e.g., 10us+
|
|
selects a slower clock (producing an interval of at least 10 us).
|
|
|
|
|
|
Clock output
|
|
------------
|
|
|
|
# ubb-patgen -c
|
|
|
|
outputs a clock on CLK. The default is 1 MHz and can be changed
|
|
with the option -f.
|
|
|
|
ubb-patgen exits and leaves the clock running. To wait for a
|
|
while and clean up on exit, add the delay in seconds, e.g.:
|
|
|
|
# ubb-patgen -f 500kHz -c 10
|
|
|
|
The delay can be followed by "m", "u", or "n" for the respective
|
|
multiplier. Furthermore, it can end with an optional "s". Note
|
|
that the minimum time ubb-patgen actually spends generating a
|
|
clock will typically be in the order of several milliseconds.
|
|
|
|
To stop the MMC bus clock, run
|
|
|
|
# ubb-patgen -c 0
|
|
|
|
|
|
Pattern output
|
|
--------------
|
|
|
|
# ubb-patgen 0110
|
|
|
|
first sets the DATx lines to 0, then outputs a 1 bit on DAT0 for
|
|
two clock cycles, and returns DAT0 to zero.
|
|
|
|
Each digit is a nibble representing the four DATx lines, with DAT0
|
|
having the value 1, DAT1 2, DAT2 4, and DAT3 8.
|
|
|
|
The repetition of a nibble can also be expressed by following it
|
|
with the number of repetitions in curly braces, e.g.,
|
|
|
|
# ubb-patgen 01{2}0
|
|
|
|
The options -f and -q work as usual.
|
|
|
|
The clock is normally not output but can be activated with the
|
|
option -C. Note that the clock output is not continuous in this
|
|
case.
|
|
|
|
The pattern can be read from a file. All whitespace is ignored
|
|
and so are comments beginning with #:
|
|
|
|
# cat <<EOF >pattern-file
|
|
1 # idle state is high
|
|
# send two characters in RS232 format
|
|
0 00010010 1 # "H"
|
|
0 10010110 1 # "i"
|
|
0 10000100 1 # "!"
|
|
0 10110000 1 # CR
|
|
1 # return to idle (high)
|
|
EOF
|
|
# ubb-patgen -f 115.2k pattern-file
|
|
|
|
If a file with the same name as a pattern exists, ubb-patgen will
|
|
try to load that file. This can be prevented with the option -p.
|
|
|
|
If only some of the DATx lines should be used for pattern output,
|
|
the option -m MASK can be used to leave the unused lines in their
|
|
previous state. MASK is a value in C syntax. Only lines whose bit
|
|
is set are used for pattern output.
|
|
|
|
|
|
External trigger
|
|
----------------
|
|
|
|
ubb-patgen normally sends the pattern immediately. This can be
|
|
delayed by waiting for an external trigger with the option -t.
|
|
|
|
# ubb-patgen -t 0 0f0
|
|
|
|
configures CLK as an input, waits for it to become zero, and then
|
|
outputs the 010 pattern. If CLK is already zero, ubb-patgen will
|
|
send the pattern immediately.
|
|
|
|
Likewise, -t 1 waits for CLK to become 1. -t cannot be used with
|
|
the -C option.
|
|
|
|
The trigger can also be a sequence, e.g., -t 01 would first wait
|
|
for CLK to become zero (if it isn't already), then wait for it to
|
|
become one.
|
|
|
|
ubb-patgen usually starts the pattern about 2-10 us after the
|
|
trigger, but this can be delayed by other system activity. An
|
|
extra delay can be added with the option -w, e.g.,
|
|
|
|
# ubb-patgen -t 0 -w 1s 010
|
|
|
|
The trigger signal can be debounced with the option -d, e.g.,
|
|
|
|
# ubb-patgen -t 0 -d 100us 0f0
|
|
|
|
This accepts the trigger only after it has been zero for at least
|
|
100 microseconds. If the trigger is a sequence, debouncing is
|
|
applied at each step.
|