Pulsebox channel to pin mappings

Pulsebox channels and their mapping to Arduino Due digital pins.

Pulsebox channels

The Arduino pins for the pulsebox channels are chosen so that they all belong to a single PIO PORT (PORTC). This allows us to change the state of the pulsebox with just one instruction - a write into the REG_PIOC_ODSR register. PORTC was chosen because it contained the largest number of free general-purpose digital pins (26).

Following are the default pin assignments (see the picture above). The sixteen pins were chosen because of their mutual proximity.

channel	PORTC bit	Arduino pin
1	1	33
2	3	35
3	5	37
4	7	39
5	9	41
6	18	45
7	16	47
8	14	49
9	12	51
10	2	34
11	4	36
12	6	38
13	8	40
14	19	44
15	17	46
16	15	48

In principle, there are 26 PORTC pins available. The following table (based on a similar table found in the Arduino Due documentation) lists them all:

PORTC bit	Arduino pin	Mapped pin name
1	33	Digital pin
2	34	Digital pin
3	35	Digital pin
4	36	Digital pin
5	37	Digital pin
6	38	Digital pin
7	39	Digital pin
8	40	Digital pin
9	41	Digital pin
12	51	Digital pin
13	50	Digital pin
14	49	Digital pin
15	48	Digital pin
16	47	Digital pin
17	46	Digital pin
18	45	Digital pin
19	44	Digital pin
21	9	Digital pin
22	8	Digital pin
23	7	Digital pin
24	6	Digital pin
25	5	Digital pin
26	4	Digital pin
28	3	Digital pin
29	10	Digital pin
30	72	LED RX

Trigger channel

Currently on Arduino pin 52. The trigger pin does not have to belong to the same PORT as the pulsebox pins. Again, we have chosen pin 52 because of its proximity to the pulsebox pins.