Electronics Projects, ARM LPC2138 microcontroller based digital audio player article
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Flash Card Audio Player for Head End Unit This project uses an LPC213x to implement a simple digital audio player, capable of playing music tracks from a removable flash card. The player is controlled using the component-bus interface from a car audio head-end unit, and provides a line out stereo signal, suitable for plugging into the auxiliary input connector of the head-end unit. Author: Lindsay Meek
TOOLCHAIN GCC within Keil uVision
CPU CLOCK 60 MHz
UARTS 1 (For In-circuit programming and debugging)
INPUT CAPTURES 1
GPIO USED 15 (Include Peripherals)
MODES Thumb (Background), ARM (IRQs)
TARGETS LPC2132, LPC2134, LPC2136, LPC2138
LPC2131 with a smaller DAC sample buffer
Head End Protocol Disrupt
The head-end protocol program consisted of a SPI-like servile , with a concentrated bi-directional accumulation connexion, with a 1ms gap between bytes, and a 50ms+ gap between packets.
As no SPI skirting was free on the LPC213x to cater the low-level byte program, a bit-banging software act was victimized. This operated using Timer1, with a compounding of slip charm on the bus timekeeper differentiation and oscillating counters.