Broadcom BCM2835

The first channel to be received will be the first

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Unformatted text preview: filter. PDM Input Mode Enable 0 = Disable PDM (classic PCM input). 1 = Enable PDM input filter. Enable CIC filter on input pin for PDM inputs. In order to receive data RXON must also be set. Receive Frame Packed Mode 0 = The data from each channel is written into the RX FIFO. 1 = The data from both RX channels is merged (1st channel is in the LS half) and then written to the RX FIFO as a single 2x16 bit packed mode word. First received channel in the frame goes into the LS half word. If the received data is larger than 16 bits, the upper bits are truncated. The maximum channel size is 16 bits. Transmit Frame Packed Mode 0 = Each TX FIFO word is written into a single channel. 1 = Each TX FIFO word is split into 2 16 bit words and used to fill both data channels in the same frame. The maximum channel size is 16 bits. The LS half of the word is used in the first channel of the frame. PCM Clock Mode 0 = Master mode. The PCM CLK is an output and drives at the MCLK rate. 1 = Slave mode. The PCM CLK is an input. RW 0x0 27 PDMN RW 0x0 26 PDME RW 0x0 25 FRXP RW 0x0 24 FTXP RW 0x0 23 CLKM RW 0x0 06 February 2012 Broadcom Europe Ltd. 406 Science Park Milton Road Cambridge CB4 0WW 2012 Broadcom Corporation. All rights reserved Page 130 22 CLKI Clock Invert this logically inverts the PCM_CLK signal. 0 = Outputs change on rising edge of clock, inputs are sampled on falling edge. 1 = Outputs change on falling edge of clock, inputs are sampled on rising edge. Frame Sync Mode 0 = Master mode. The PCM_FS is an output and we generate the frame sync. 1 = Slave mode. The PCM_FS is an input and we lock onto the incoming frame sync signal. Frame Sync Invert This logically inverts the frame sync signal. 0 = In master mode, FS is normally low and goes high to indicate frame sync. In slave mode, the frame starts with the clock where FS is a 1 after being a 0. 1 = In master mode, FS is normally high and goes low to indicate frame sync. In slave mode, the frame starts with the clock where FS is a 0 after being a 1. Frame Length Sets the frame length to (FLEN+1) clocks. Used only when FSM == 0. 1 = frame length of 2 clocks. 2 = frame length of 3 clocks. etc Frame Sync Length Sets the frame sync length to (FSLEN) clocks. This is only used when FSM == 0. PCM_FS will remain permanently active if FSLEN >= FLEN. 0 = frame sync pulse is off. 1 = frame sync pulse is 1 clock wide. etc RW 0x0 21 FSM RW 0x0 20 FSI RW 0x0 19:10 FLEN RW 0x0 9:0 FSLEN RW 0x0 RXC_A Register Synopsis Sets the Channel configurations for Receiving. This sets the position and width of the 2 receive channels within the frame. The two channels cannot overlap, however they channel 1 can come after channel zero, although the first data will always be from the first channel in the frame. Channels can also straddle the frame begin end boundary as that is set by the frame sync position. This register cannot be changed whilst the PCM is running. Description Type Reset Bit(s) Field Name 06 February 2012 Broadcom Europe Ltd. 406 Science Park Milton Road Cambridge CB4 0WW 2012 Broadcom Corporation. All rights reserved Page 131 31 CH1WEX Channel 1 Width Extension Bit This is the MSB of the channel 1 width (CH1WID). It allows widths greater than 24 bits to be programmed and is added here to keep backwards compatibility with older versions of the PCM Channel 1 Enable 0 = Channel 1 disabled and no data is received from channel 1 and written to the RX FIFO. 1 = Channel 1 enabled. Channel 1 Position This sets the bit clock at which the first bit (MS bit) of channel 1 data occurs in the frame. 0 indicates the first clock of frame. Channel 1 Width This sets the width of channel 1 in bit clocks. This field has been extended with the CH1WEX bit giving a total width of (CH1WEX* 16) + CH1WID + 8. The Maximum supported width is 32 bits. 0 = 8 bits wide 1 = 9 bits wide Channel 2 Width Extension Bit This is the MSB of the channel 2 width (CH2WID). It allows widths greater than 24 bits to be programmed and is added here to keep backwards compatibility with older versions of the PCM Channel 2 Enable 0 = Channel 2 disabled and no data is received from channel 2 and written to the RX FIFO. 1 = Channel 2 enabled. Channel 2 Position This sets the bit clock at which the first bit (MS bit) of channel 2 data occurs in the frame. 0 indicates the first clock of frame. Channel 2 Width This sets the width of channel 2 in bit clocks. This field has been extended with the CH2WEX bit giving a total width of (CH2WEX* 16) + CH2WID + 8. The Maximum supported width is 32 bits. 0 = 8 bits wide 1 = 9 bits wide RW 0x0 30 CH1EN RW 0x0 29:20 CH1POS RW 0x0 19:16 CH1WID RW 0x0 15 CH2WEX RW 0x0 14 CH2EN RW 0x0 13:4 CH2POS RW 0x0 3:0 CH2WID RW 0x0 06 February 2012 Broadcom Europe Ltd. 406 Science Park Milton Road Cambridge CB4 0WW 2012 Broadcom Corporation. All rights reserved Page 132 TXC_A Register Synopsis Sets the Channel configurations for Transmitting. This sets the position and width of the 2 transmit channels within the frame. The two...
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This note was uploaded on 04/17/2013 for the course EEC 193 taught by Professor Kevin during the Spring '13 term at UC Davis.

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