Broadcom BCM2835

Sd14 sd15 sd16 sd17 reserved reserved sa5 sa4 sa3 sa2

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Unformatted text preview: ; <Internal> <Internal> <Internal> SD5 SD6 SD7 SDA0 SCL0 <reserved> <reserved> <reserved> SDA1 SCL1 <reserved> <reserved> <reserved> <reserved> <reserved> SPI2_MOSI SPI2_SCLK SPI2_CE0_N SPI2_CE1_N SPI2_CE2_N RXD1 RTS1 CTS1 Table 6-31 GPIO Pins Alternative Function Assignment Entries which are white should not be used. These may have unexpected results as some of these have special functions used in test mode. e.g. they may drive the output with high frequency signals. Special function legend: Name SDA0 SCL0 SDA1 SCL1 GPCLK0 GPCLK1 GPCLK2 SPI0_CE1_N SPI0_CE0_N SPI0_MISO SPI0_MOSI SPI0_SCLK PWMx TXD0 RXD0 CTS0 RTS0 PCM_CLK PCM_FS PCM_DIN PCM_DOUT SAx SOE_N / SE SWE_N / SRW_N SDx BSCSL SDA / MOSI BSCSL SCL / SCLK BSCSL - / MISO BSCSL - / CE_N Function 6 BSC master 0 data line BSC master 0 clock line BSC master 1 data line BSC master 1 clock line General purpose Clock 0 General purpose Clock 1 General purpose Clock 2 SPI0 Chip select 1 SPI0 Chip select 0 SPI0 MISO SPI0 MOSI SPI0 Serial clock Pulse Width Modulator 0..1 UART 0 Transmit Data UART 0 Receive Data UART 0 Clear To Send UART 0 Request To Send PCM clock PCM Frame Sync PCM Data in PCM data out Secondary mem Address bus Secondary mem. Controls Secondary mem. Controls Secondary mem. data bus BSC slave Data, SPI salve MOSI BSC slave Clock, SPI slave clock BSC <not used>,SPI MISO BSC <not used>, SPI CSn See section BSC BSC BSC BSC <TBD> <TBD> <TBD> SPI SPI SPI SPI SPI Pulse Width Modulator UART UART UART UART PCM Audio PCM Audio PCM Audio PCM Audio Secondary Memory Interface Secondary Memory Interface Secondary Memory Interface Secondary Memory Interface BSC ISP slave BSC ISP slave BSC ISP slave BSC ISP slave 6 The Broadcom Serial Control bus is a proprietary bus compliant with the Philips I2C bus/interface 06 February 2012 Broadcom Europe Ltd. 406 Science Park Milton Road Cambridge CB4 0WW 2012 Broadcom Corporation. All rights reserved Page 103 Name SPI1_CEx_N SPI1_MISO SPI1_MOSI SPI1_SCLK TXD0 RXD0 CTS0 RTS0 SPI2_CEx_N SPI2_MISO SPI2_MOSI SPI2_SCLK ARM_TRST ARM_RTCK ARM_TDO ARM_TCK ARM_TDI ARM_TMS Function SPI1 Chip select 0-2 SPI1 MISO SPI1 MOSI SPI1 Serial clock UART 1 Transmit Data UART 1 Receive Data UART 1 Clear To Send UART 1 Request To Send SPI2 Chip select 0-2 SPI2 MISO SPI2 MOSI SPI2 Serial clock ARM JTAG reset ARM JTAG return clock ARM JTAG Data out ARM JTAG Clock ARM JTAG Data in ARM JTAG Mode select See section Auxiliary I/O Auxiliary I/O Auxiliary I/O Auxiliary I/O Auxiliary I/O Auxiliary I/O Auxiliary I/O Auxiliary I/O Auxiliary I/O Auxiliary I/O Auxiliary I/O Auxiliary I/O <TBD> <TBD> <TBD> <TBD> <TBD> <TBD> 06 February 2012 Broadcom Europe Ltd. 406 Science Park Milton Road Cambridge CB4 0WW 2012 Broadcom Corporation. All rights reserved Page 104 6.3 General Purpose GPIO Clocks The General Purpose clocks can be output to GPIO pins. They run from the peripherals clock sources and use clock generators with noise-shaping MASH dividers. These allow the GPIO clocks to be used to drive audio devices. The fractional divider operates by periodically dropping source clock pulses, therefore the output frequency will periodically switch between: source _ frequency DIVI & source _ frequency DIVI + 1 Jitter is therefore reduced by increasing the source clock frequency. In applications where jitter is a concern, the fastest available clock source should be used. The General Purpose clocks have MASH noise-shaping dividers which push this fractional divider jitter out of the audio band. MASH noise-shaping is incorporated to push the fractional divider jitter out of the audio band if required. The MASH can be programmed for 1, 2 or 3-stage filtering. MASH filter, the frequency is spread around the requested frequency and the user must ensure that the module is not exposed to frequencies higher than 25MHz. Also, the MASH filter imposes a low limit on the range of DIVI. MASH 0 (int divide) 1 2 3 min DIVI 1 2 3 5 min output freq source / ( DIVI ) source / ( DIVI ) source / ( DIVI - 1 ) source / ( DIVI - 3 ) average output freq source / ( DIVI ) source / ( DIVI + DIVF / 1024 ) source / ( DIVI + DIVF / 1024 ) source / ( DIVI + DIVF / 1024 ) max output freq source / ( DIVI ) source / ( DIVI + 1 ) source / ( DIVI + 2 ) source / ( DIVI + 4 ) Table 6-32 Effect of MASH Filter on Frequency The following example illustrates the spreading of output clock frequency resulting from the use of the MASH filter. Note that the spread is greater for lower divisors. PLL freq (MHz) 650 650 650 650 400 400 400 400 200 200 200 200 target freq (MHz) 18.32 18.32 18.32 18.32 18.32 18.32 18.32 18.32 18.32 18.32 18.32 18.32 MASH 0 1 2 3 0 1 2 3 0 1 2 3 divisor 35.480 35.480 35.480 35.480 21.834 21.834 21.834 21.834 10.917 10.917 10.917 10.917 DIVI 35 35 35 35 21 21 21 21 10 10 10 10 DIVF 492 492 492 492 854 854 854 854 939 939 939 939 min freq (MHz) 18.57 18.06 17.57 16.67 19.05 18.18 17.39 16.00 20.00 18.18...
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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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