This paper presents the simulation study of nonlinear dynamic of cardiac excitation based on Luo Rudy Phase I (LR-I) model towards numerical solutions of ordinary differential equations (ODEs) responsible for cardiac excitation on field programmable gate arrays (FPGAs). As computational modeling needs vast of simulation time, a real-time hardware implementation using FPGA could be the solution as it provides high configurability and performance. For rapid prototyping, MATLAB Simulink that offers a link with the FPGA has been used. Through Simulink HDL Coder, a tool in the MATLAB software that capable to convert the MATLAB Simulink blocks into hardware description language (HDL) code and an FPGA-in-the-loop (FIL) and co-simulation for verification, FPGA hardware implementation can be done. As a result, the LR-I excitation model is successfully simulated by using the MATLAB Simulink and the VHDL code has been successfully generated by the HDL Coder after fixed-point optimization is done. The FIL verification on actual FPGA board also has shown quantitatively comparable results to the MATLAB Simulink simulation. Therefore, the design flow has given a positive outlook in developing this FPGA stand-alone implementation.