I can not find the DAC function in nrf51822.

Question

I want to operate 
 Tries to operate a small speaker. 
 www.wvshare.com/.../Analog-Test-Board.htm 
 but I can not find the DAC function in nrf51822. 
 How do I create the Analog signal?

Stian Røed Hafskjold · Accepted Answer

There is no DAC on the nRF51. You have to use PWM on one of the GPIOs on order to get sound from the chip. We have a PWM library on Github here: github.com/.../nrf51-pwm-library , and it also includes a sound example. 
 If you want a simpler example, just how to set up the PWM and play back a sound clip, you can have a look at the following example code. It is based on SDK 6.1.0. The main.c file sets up the timer, GPIOTE and PPI to control the pulse width on one of the GPIOs (PWM). The sound clip is stored as an array of uint8_t type samples in the sound.h file 
 Download: 
 main.c and
 sound.h