1. A computer implemented method for implementing a convolutional neural network (CNN) using resistive processing unit (RPU) array, the method comprising: configuring an RPU array corresponding to a convolution layer in the CNN based on convolution kernels of the convolution layer; performing forward pass computations for the CNN via the RPU array by: transmitting voltage pulses corresponding to input data of the convolution layer to the RPU array; and storing values corresponding to output currents from the RPU arrays as output maps; performing backward pass computations for the CNN via the RPU array by: transmitting voltage pulses corresponding to error of the output maps of the convolution layer to the RPU array; and storing values corresponding to the output currents from the RPU arrays as backward error maps; performing update pass computations for the CNN via the RPU array by: transmitting voltage pulses corresponding to the input data of the convolution layer and the error of the output maps to the RPU array.