This paper concerns the nonlinear 1D FitzHugh Nagumo system with a Robin boundary control. We prove that this system is ”flat-like” with the outflow electrical potential playing the role of the flat output. Indeed, the solution can be expressed in terms of an infinite series depending on the derivatives and the integrals of the flat output. This series is shown to be convergent provided that the flat output is Gevrey of order 1 < a ≤ 2. Numerical simulations are also presented.