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. 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 To stop the MMC bus clock, run # ubb-patgen -c 0 ubb-patgen warns if the selected frequency does not match the requested frequency, e.g., # ubb-patgen -f 100kHz -c bus clk = 100.962 kHz (+0.96%) This warning can be suppressed with the option -q. 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 <pattern-file 1 # idle state is high # send two characters in RS232 format 0 00010010 1 # "H" 0 10010110 1 # "i" 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. ubb-patgen usually starts the pattern about 2 us after the trigger, but this can be delayed by other system activity.