107 lines
4.2 KiB
C
107 lines
4.2 KiB
C
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/*
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* Copyright 2018 Hillcrest Laboratories, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License and
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* any applicable agreements you may have with Hillcrest Laboratories, Inc.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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/*
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* SH2 HAL Interface for Non-RTOS Applications.
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*/
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// Include guard
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#ifndef SH2_HAL_H
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#define SH2_HAL_H
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#include <stdint.h>
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// SH2 Implementations generally have a max out transfer len of 256
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#define SH2_HAL_MAX_TRANSFER_OUT (256)
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#define SH2_HAL_MAX_PAYLOAD_OUT (256)
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// Although some implementations adversize a max in transfer of 32K,
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// in practice, the largest transfer performed is the advertisements
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// which is 272 bytes at time of writing.
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#define SH2_HAL_MAX_TRANSFER_IN (384)
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#define SH2_HAL_MAX_PAYLOAD_IN (384)
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// This needs to be a power of 2, greater than max of the above.
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#define SH2_HAL_DMA_SIZE (512)
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typedef struct sh2_Hal_s sh2_Hal_t;
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// The SH2 interface uses these functions to access the underlying
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// communications device, so the system integrator will need to
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// implement these. At system intialization time, an sh2_Hal_t
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// structure should be initialized with pointers to all the hardware
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// access layer functions. A pointer to this structure must then be
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// passed to sh2_open() to initialize the SH2 interface.
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//
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// If the DFU (download firmware update) capability is needed, the
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// example DFU code also uses this interface but each function has
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// somewhat different requirements. So a separate instance of an
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// sh2_Hal_t structure, pointing to different functions, is
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// recommended for supporting DFU.
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struct sh2_Hal_s {
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// This function initializes communications with the device. It
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// can initialize any GPIO pins and peripheral devices used to
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// interface with the sensor hub.
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// It should also perform a reset cycle on the sensor hub to
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// ensure communications start from a known state.
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int (*open)(sh2_Hal_t *self);
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// This function completes communications with the sensor hub.
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// It should put the device in reset then de-initialize any
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// peripherals or hardware resources that were used.
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void (*close)(sh2_Hal_t *self);
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// This function supports reading data from the sensor hub.
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// It will be called frequently to sevice the device.
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//
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// If the HAL has received a full SHTP transfer, this function
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// should load the data into pBuffer, set the timestamp to the
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// time the interrupt was detected and return the non-zero length
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// of data in this transfer.
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//
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// If the HAL has not recevied a full SHTP transfer, this function
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// should return 0.
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//
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// Because this function is called regularly, it can be used to
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// perform other housekeeping operations. (In the case of UART
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// interfacing, bytes transmitted are staggered in time and this
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// function can be used to keep the transmission flowing.)
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int (*read)(sh2_Hal_t *self, uint8_t *pBuffer, unsigned len, uint32_t *t_us);
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// This function supports writing data to the sensor hub.
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// It is called each time the application has a block of data to
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// transfer to the device.
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//
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// If the device isn't ready to receive data this function can
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// return 0 without performing the transmit function.
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//
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// If the transmission can be started, this function needs to
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// copy the data from pBuffer and return the number of bytes
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// accepted. It need not block. The actual transmission of
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// the data can continue after this function returns.
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int (*write)(sh2_Hal_t *self, uint8_t *pBuffer, unsigned len);
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// This function should return a 32-bit value representing a
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// microsecond counter. The count may roll over after 2^32
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// microseconds.
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uint32_t (*getTimeUs)(sh2_Hal_t *self);
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};
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// End of include guard
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#endif
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