NXP Semiconductors LPC43 Series User Manual

Contents

NXP Semiconductors LPC43 Series User Manual Manual pdf 444 page image

UM10503 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2012. All rights reserved.User manual Rev. 1.3 — 6 July 2012 444 of 1269NXP Semiconductors UM10503Chapter 20: LPC43xx SD/MMC interface– Check if response_timeout error, response_CRC error, or response error is set.This can be done either by responding to an interrupt raised by these errors or bypolling bits 1, 6, and 8 from the RINTSTS register @0x44. If no response error isreceived, then the response is valid. If required, the software can copy theresponse from the response registers @0x30-0x3C.Software should not modify clock parameters while a command is being executed.20.7.4.5 Data Transfer CommandsData transfer commands transfer data between the memory card and the Module. To senda data command, the Module needs a command argument, total data size, and block size.Software can receive or send data through the FIFO.Before a data transfer command, software should confirm that the card is not busy and isin a transfer state, which can be done using the CMD13 and CMD7 commands,respectively.Table 331. CMD register settings for No-Data CommandName Value Commentstart_cmd 1update_clock_ registers_only 0 No clock parameters update commandcard_number 0 Card number in use. Only zero is possiblebecause one card is support.Data_expected 0 No data command.Send_initialization 0 Can be 1, but only for card reset commands,such as CMD0stop_abort_cmd 0 Can be 1 for commands to stop data transfer,such as CMD12Cmd_index Command indexResponse_length 0 Can be 1 for R2 (long) responseResponse_expect 1 Can be 0 for commands with no response; forexample, CMD0, CMD4,CMD15, and so onUser-selectableWait_prvdata_complete 1 Before sending command on command line,cpu should wait forcompletion of any data command in process,if any (recommended toalways set this bit, unless the currentcommand is to query status or stopdata transfer when transfer is in progress)Check_response_crc 1 0 – Do not check response CRC1 – Check response CRCSome of command responses do not returnvalid CRC bits. Software should disable CRCchecks for those commands in order todisable CRC checking by controller.