Skip to content

Latest commit

 

History

History

rotenc16

Folders and files

NameName
Last commit message
Last commit date

parent directory

..
src
src
 
 
Makefile
Makefile
 
 
demo.jpg
demo.jpg
 
 
readme.md
readme.md
 
 
schematic.jpg
schematic.jpg
 
 

readme.md

GM-PROTO-E1 Example "rotenc16"

This Verilog example program validates the function of a single 16-position rotary encoder, soldered into the prototyping area of the GM-Proto-E1 board. I am using model ERD216RSZ from vendor Excel Cell Electronics (ECE). 16-position rotary encoders are convenient as data input. With two encoders it is possble to quickly set the hex value of one byte.

Schematic

Verilog Code

Verilog code is likewise very simple. The encoder input signal pins can be assigned directly as bit values of one nibble (half-byte). On the GM-Proto-E1 board, we can map the encoder signal bit range straight to the 4 output LED's, and to one of the 7-segment LED displays to show the value in hex.

// -------------------------------------------------------
// rotenc16.v   gm-proto-e1 demo program   @20230528 fm4dd
//
// Requires: 4x LEDs, 16-pos rotary encoder, 1x 7-Seg LED
//
// Description:
// ------------
// This program shows the rotary encoder signal on LED0-3,
// and the corresponding hex code on 7-seg display prhex0.
// -------------------------------------------------------
module rotenc16(
  input wire [3:0] prrot,
  output wire [3:0] prled,
  output [7:0] prhex0
);

// -------------------------------------------------------
//  Module hexdigit: Creates the LED pattern from 3 args:
// in:  0-16 sets hex value of led segments, >16 is extra
// dp:  0 or 1, disables/enables the decimal point led
// out: this is the bit pattern for the 7seg module led's
//
// Note: Because 'in' is 5-bit wide to display extra chars
// we set the unused highest bit in[4] to 0, and assign
// the prrot signal to the remaining bits at in[3:0].
// -------------------------------------------------------
  hexdigit h0 ({1'b0, prrot}, 1'b0, prhex0);
  assign prled = prrot;
endmodule

Pin assignment

added in src/gm-proto-e1.ccf:

## #######################################################
## gm-proto-e1 proto area 16-pos rotary encoder connection
## #######################################################
Pin_in "prrot[0]"    Loc = "IO_SB_B0" | PULLDOWN=true;
Pin_in "prrot[1]"    Loc = "IO_SB_B1" | PULLDOWN=true;
Pin_in "prrot[2]"    Loc = "IO_SB_B2" | PULLDOWN=true;
Pin_in "prrot[3]"    Loc = "IO_SB_B3" | PULLDOWN=true;

Usage

fm@nuc7vm2204:~/fpga/hardware/gm-proto-e1/examples-tht/rotenc16$ make all
/home/fm/cc-toolchain-linux/bin/yosys/yosys -ql log/synth.log -p 'read -sv src/hexdigit.v src/rotenc16.v; synth_gatemate -top rotenc16 -nomx8 -vlog net/rotenc16_synth.v'
/home/fm/cc-toolchain-linux/bin/p_r/p_r -i net/rotenc16_synth.v -o rotenc16 -ccf src/gm-proto-e1-tht.ccf > log/impl.log
/usr/local/bin/openFPGALoader  -b gatemate_evb_jtag rotenc16_00.cfg
Jtag frequency : requested 6.00MHz   -> real 6.00MHz  
Load SRAM via JTAG: [==================================================] 100.00%
Done
Wait for CFG_DONE DONE