973 Send Receive :: Quicker, easier and cheaper to make your own chip!

How it works

Send Recieve Project Description

A simple 4-value send/receive chip

This project realizes a very simple 4-value sender and receiver chip. The mode of the chip is determined by input 7: sender low, receiver high. Currently, the protocol only supports 1 sender and 1 receiver.

Sender Mode

Sender mode is enabled when Input[7] is set low. In sender mode, the chip looks for a rising value on bits 0:4 of the input bus. This can be achieved through the use of a 4-button PMOD module, or by toggling the corresponding DIP switch on the carrier board.

Sender Mode Input:

#	Input	Description
0	input[0]	bit[0] to send
1	input[1]	bit[1] to send
2	input[2]	bit[2] to send
3	input[3]	bit[3] to send
4	unused	N/A
5	unused	N/A
6	unused	N/A
7	input[7]	Sender/Receiver indicator

To send data, the sender pulls Output[0] high and relays the corresponding input bit (i) on Output[i+1] (Note: currently only one bit can be sent at a time). The Sender also sets Output[7] to indicate to the connected chip that it should operate in receiver mode.

Finally, The sender keeps Output[0] high long enough to prevent the receiver's debounce filtering from masking the signal before setting it low again.

Sender Mode Output:

#	Output	Description
0	Transmit	Signal receiver to read data
1	x_bit[0]	Transmit bit[0]
2	x_bit[1]	Transmit bit[1]
3	x_bit[2]	Transmit bit[2]
4	x_bit[3]	Transmit bit[3]
5	unused	N/A
6	unused	N/A
7	Mode_of_connected_chip	Sender/Receiver indicator

Receiver Mode

Receiver mode is enabled when Input[7] is set high. In receiver mode, the chip listens on Input[0:5]. It waits until the positive edge of Input[0] before registering an input.

Receiver Mode Input:

#	Input	Description
0	Read	Read input bits
1	input[0]	recv_ bit[0]
2	input[1]	recv_ bit[1]
3	input[2]	recv_ bit[2]
4	input[3]	recv_ bit[3]
5	unused	N/A
6	unused	N/A
7	input[7]	Sender/Receiver indicator

The chip utilizes the carrier chip's 7 segment display to echo a value corresponding to the input data:

Input[1:4]	Output Value	Display Value
1000	0000_0110	1
0100	0101_1011	2
0010	0110_0110	4
0001	0111_1111	8

The receiver initially displays zero (on the 7-segment display) until it receives the read signal from the sender. The receiver then displays the value received or an E when the value is not 1, 2, 4, and 8. The last value received, or E is displayed until the receives gets the signal to read the next value.

How to test

To connect two chips, configure them as follows:

Sender
- Inputs: (Choose One)
  - None (i.e. the chip will read data from the carrier chip's DIP switches)
  - 6-pin, 4-button PMOD keypad plugged into Input[0-5] (top row)
- Outputs:
  - Connect all 12 output pins to the inputs on the receiver
Receiver
- Inputs
  - Power, ground, and all 8 data pins from the sender must be connected to the receiver's corresponding inputs. This requires the use of a specially crafted cross-over cable to ensure the correct connections.

picture of two chips connected as sender-receiver

External hardware

PMOD 4 button keypad

#	Input	Output
0	Input[0]/Message Ready	Transmit/LCD Display Value[0]
1	Input[1]/recv_bit[0]	input[0]/LCD Display Value[1]
2	Input[2]/recv_bit[1]	Input[1]/LCD Display Value[2]
3	Input[3]/recv_bit[2]	Input[2]/LCD Display Value[3]
4	unused/recv_bit[3]	Input[3]/LCD Display Value[4]
5	unused	unused/LCD Display Value[5]
6	unused	unused/LCD Display Value[6]
7	Sender/Receiver Mode Select (0/1)	Mode of connected chip//LCD Display Value[7]

973 Send Receive

973 : Send Receive