Today's multimedia and DSP applications impose requirements on performance and power consumption that only custom processor architectures with SIMD capabilities can satisfy. However, the specific features of such architectures, including vector operations and high-bandwidth complex memory organization, make them notoriously complicated and time consuming to program. In this paper we present an automated code generation approach that dramatically reduces the effort of programming such architectures, by carrying out instruction scheduling and memory allocation based on a constraint programming formulation. Furthermore, the quality of the generated code is close to that of hand-written code by an experienced programmer with knowledge of the architecture. We demonstrate the viability of our approach on an existing custom heterogeneous DSP architecture, by compiling and running a number of typical DSP kernels, and comparing the results to hand-optimized code.