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Purpose:
The pedal board reads the ADCs for the throttle and brake pedals and broadcasts the data to the MCI.
Implementation:
The pedal project will consist of 1 task, the master_task. It will also use CAN. The master task will run in the main.c file, and this file will also have init_pedal_controls to initialize the MAX11600 IC and the necessary GPIOs. The main.c file will include the header for the IC, which should be written under the [library name] library, and will also include pedal_data.h, written under the pedal project, which uses the IC to read the pedal angle of both throttle and brake.
The pedal’s calibration will be taken care of in a test file called test_pedal_calibrate, which will be structured as a test but act as the pedal’s calibration functionality. This test will have it’s own dependencies, pedal_calib.h/.c.
main.c
The main file should initialize CAN, all the tasks, and any other modules that will be used. The file should look like the standard main.c for every project. Use scons new --project=pedal to make a new project.
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pedal_calibrate needs to read the ADC when the throttle and brake are pressed down, and when they are let go, and use that reading to set the upper and lower bounds of the pedal (subject to change, based off of MSXIV).
pedal_data.c
The pedal data file should have two functions, read_throttle_data, and read_brake_data, each of which reads the respective channel from the IC over I2C. These functions should update the values using the pointer passed into it and should return a StatusCode. The data read from these functions should be adjusted based on calibration.
test_pedal_calib.c
This should mostly be copied from MSXIV but will depend on a lot of files that need to be ported over.
max11600.c
General idea - The MAX11600 has four analog IN channels, AIN0 is throttle, AIN1 is steering angle, and AIN2 is brake, and AIN3 is used as a reference voltage (hardware’s problem). The MAX will scan from AIN0 up to AIN2 and send each of these channels' readings in sequence. We can discard the reading from AIN1 (unless we need it in the future), and use the other two channels we’re reading and return those values to whichever function is requesting themunused. We’ll send a configuration byte to select a channel and then simply read in the data from that channel. Taken from Figure 11 on the datasheet:
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The driver should send the slave address with a read byte (11001001), after which the MAX will begin sending AIN0-2 the data from the selected channel until the master transmits a STOP condition (for us this will be done will just two function calls).
max11600_init:
Send a setup and configuration byte to the IC (address 11001000) and set up any necessary storage/struct pointers needed for the driver.
Byte | Bits |
|---|---|
Setup | 101x100x |
Configuration |
011xx001 These are channel select bits which need to be changed depending on the data we’re reading - they can be anything on initialization |
View Tables 1 and 2 on the datasheet for more information on Setup and Configuration bytes.
max11600_read_raw:
Send the slave Slave address 11001000 - write a config byte to select channel.
Slave address 11001001, - read in three values in binary, discard the steering value, transmit STOP condition.the data
This function should be passed a pointer to a storage variable/struct which will hold the three values read from the MAX.
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Calls max11600_read_raw, then converts the values to the value in mV. Look at Figure 12 on the datasheet to understand how to convert from binary to mV.
CAN Messages:
See pedal.yaml
Message | Id | Target | Data | Types |
|---|---|---|---|---|
| 18 |
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TODO:
Steering angle sensor
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