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ManojBR105 / Teensy-4.0_digital_parallel_read-write

This Repository consists of functions to read and write data to multiple pin with high speed on Teensy4.0
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Parallel Digital READ/WRITE

This Repository consists of functions to read and write data to multiple pins with high speed on Teensy4.0 with the help of port manipulation.
It uses only breadboard friendly pins(0-23) and has been optimised to consume less time as much as possible.
The pins are optimised to take less memory and execution and should not be changed.
(*changing pins requires lot of changes in the code.)

There are 5 options for number of bits.

There are four operations for each option.

8 BIT pinmap:

PINS PORT INT_BIT DATA_BIT
19 GPIO_6 16 0
18 GPIO_6 17 1
14 GPIO_6 18 2
15 GPIO_6 19 3
17 GPIO_6 22 4
16 GPIO_6 23 5
22 GPIO_6 24 6
23 GPIO_6 25 7

10 BIT pinmap:

PINS PORT INT_BIT DATA_BIT
19 GPIO_6 16 0
18 GPIO_6 17 1
14 GPIO_6 18 2
15 GPIO_6 19 3
17 GPIO_6 22 4
16 GPIO_6 23 5
22 GPIO_6 24 6
23 GPIO_6 25 7
20 GPIO_6 26 8
21 GPIO_6 27 9

12 BIT pinmap:

PINS PORT INT_BIT DATA_BIT
19 GPIO_6 16 0
18 GPIO_6 17 1
14 GPIO_6 18 2
15 GPIO_6 19 3
17 GPIO_6 22 4
16 GPIO_6 23 5
22 GPIO_6 24 6
23 GPIO_6 25 7
20 GPIO_6 26 8
21 GPIO_6 27 9
1 GPIO_6 2 10
0 GPIO_6 3 11

16 BIT pinmap:

PINS PORT INT_BIT DATA_BIT
10 GPIO_7 0 0
12 GPIO_7 1 1
11 GPIO_7 2 2
13 GPIO_7 3 3
17 GPIO_6 22 4
16 GPIO_6 23 5
22 GPIO_6 24 6
23 GPIO_6 25 7
20 GPIO_6 26 8
21 GPIO_6 27 9
1 GPIO_6 2 10
0 GPIO_6 3 11
19 GPIO_6 16 12
18 GPIO_6 17 13
14 GPIO_6 18 14
15 GPIO_6 19 15

24 BIT pinmap:

PINS PORT INT_BIT DATA_BIT
10 GPIO_7 0 0
12 GPIO_7 1 1
11 GPIO_7 2 2
13 GPIO_7 3 3
17 GPIO_6 22 4
16 GPIO_6 23 5
22 GPIO_6 24 6
23 GPIO_6 25 7
20 GPIO_6 26 8
21 GPIO_6 27 9
1 GPIO_6 2 10
0 GPIO_6 3 11
19 GPIO_6 16 12
18 GPIO_6 17 13
14 GPIO_6 18 14
15 GPIO_6 19 15
2 GPIO_9 4 16
3 GPIO_9 5 17
4 GPIO_9 6 18
5 GPIO_9 8 19
6 GPIO_7 10 20
9 GPIO_7 11 21
8 GPIO_7 16 22
7 GPIO_7 17 23

Setting pins :

set_xbit(mode);

x is no of bits and can be 8,10,12,16,24.
mode can be INPUT, INPUT_PULLUP, INPUT_PULLDOWN, OUTPUT....
this functions sets the pin as input/output it uses the usual pinMode() function with a for loop to set the pins.

Reading data :

read_xbit();

it returns the value of the data read on the pins as an unsigned integer of suitable size. Assign its value to a variable in the code.

No_of_bits type_of_return_value No_of_ports Speed
8 uint8_t 1 14ns
10 uint16_t 1 14ns
12 uint16_t 1 14ns
16 uint16_t 2 26~27ns
24 uint32_t 3 40ns

you can see that number of ports affects the speed so using less no of ports is recommonded.
*16-bit and and 24-bit can be reduced to 14ns and 27ns by using pins on the backside of the board(24,25,26,27 to be specific).

Writing data:

write_xbit(data);

x is no of bits and can be 8,10,12,16,24.
data is the parameter to be written on the data line.
This mode is faster compared to safe_write() but this method might affect other pins on the port if not managed properly.

No_of_bits parameter_type No_of_ports Speed Pins_that_might_get_affected
8 uint8_t 1 3ns 0,1,20,21,24,25,26,27
10 uint16_t 1 3ns 0,1,24,25,26,27
12 uint16_t 1 3ns 24,25,26,27
16 uint16_t 2 6~7ns 24,25,26,27,6,7,8,9,32
24 uint32_t 3 10ns 24,25,26,27,29,32,33

Again number of ports affects the speed. Speed of 16-bit and 24-bit speed can be improved to 3ns and 7ns by using pins on the backside of the board(24,25,26,27 to be specific).

safe_write_xbit(data);

This method is same as write but it doesn't affect other pins.
But it does it at the cost of the speed.		 No_of_bits Speed
8 23ns
10 23ns
12 23ns
16 43ns
24 70ns

Once again Speed of 16-bit and 24-bit speed can be improved to 23ns and 43ns by using pins on the backside of the board(24,25,26,27 to be specific).
*The speed is calculated by executing the instruction 1000 times and measuring the time taken It might not be accurate. I would like to see if anyone can probe the pins with oscilloscope and measure the speed.