SRF08 Libraray
Dependents: mbedDemoDisplay mbedDemoDisplay Roaming SRF08HelloWorld ... more
SRF08.cpp@0:752fc2753b90, 2010-08-09 (annotated)
- Committer:
- chris
- Date:
- Mon Aug 09 16:19:08 2010 +0000
- Revision:
- 0:752fc2753b90
Who changed what in which revision?
User | Revision | Line number | New contents of line |
---|---|---|---|
chris | 0:752fc2753b90 | 1 | |
chris | 0:752fc2753b90 | 2 | /* |
chris | 0:752fc2753b90 | 3 | Copyright (c) 2010 Chris Styles ( chris dot styles at mbed dot org ) |
chris | 0:752fc2753b90 | 4 | |
chris | 0:752fc2753b90 | 5 | Permission is hereby granted, free of charge, to any person obtaining a copy |
chris | 0:752fc2753b90 | 6 | of this software and associated documentation files (the "Software"), to deal |
chris | 0:752fc2753b90 | 7 | in the Software without restriction, including without limitation the rights |
chris | 0:752fc2753b90 | 8 | to use, copy, modify, merge, publish, distribute, sublicense, and/or sell |
chris | 0:752fc2753b90 | 9 | copies of the Software, and to permit persons to whom the Software is |
chris | 0:752fc2753b90 | 10 | furnished to do so, subject to the following conditions: |
chris | 0:752fc2753b90 | 11 | |
chris | 0:752fc2753b90 | 12 | The above copyright notice and this permission notice shall be included in |
chris | 0:752fc2753b90 | 13 | all copies or substantial portions of the Software. |
chris | 0:752fc2753b90 | 14 | |
chris | 0:752fc2753b90 | 15 | THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
chris | 0:752fc2753b90 | 16 | IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
chris | 0:752fc2753b90 | 17 | FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE |
chris | 0:752fc2753b90 | 18 | AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
chris | 0:752fc2753b90 | 19 | LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, |
chris | 0:752fc2753b90 | 20 | OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN |
chris | 0:752fc2753b90 | 21 | THE SOFTWARE. |
chris | 0:752fc2753b90 | 22 | */ |
chris | 0:752fc2753b90 | 23 | |
chris | 0:752fc2753b90 | 24 | #include "SRF08.h" |
chris | 0:752fc2753b90 | 25 | |
chris | 0:752fc2753b90 | 26 | |
chris | 0:752fc2753b90 | 27 | SRF08::SRF08(PinName sda, PinName scl, int addr) : m_i2c(sda, scl), m_addr(addr) { |
chris | 0:752fc2753b90 | 28 | char cmd[2]; |
chris | 0:752fc2753b90 | 29 | |
chris | 0:752fc2753b90 | 30 | // Set up SRF08 max range and receiver sensitivity over I2C bus |
chris | 0:752fc2753b90 | 31 | cmd[0] = 0x02; // Range register |
chris | 0:752fc2753b90 | 32 | cmd[1] = 0x1C; // Set max range about 100cm |
chris | 0:752fc2753b90 | 33 | m_i2c.write(m_addr, cmd, 2); |
chris | 0:752fc2753b90 | 34 | cmd[0] = 0x01; // Receiver gain register |
chris | 0:752fc2753b90 | 35 | cmd[1] = 0x1B; // Set max receiver gain |
chris | 0:752fc2753b90 | 36 | m_i2c.write(m_addr, cmd, 2); |
chris | 0:752fc2753b90 | 37 | |
chris | 0:752fc2753b90 | 38 | } |
chris | 0:752fc2753b90 | 39 | |
chris | 0:752fc2753b90 | 40 | SRF08::~SRF08() { |
chris | 0:752fc2753b90 | 41 | |
chris | 0:752fc2753b90 | 42 | } |
chris | 0:752fc2753b90 | 43 | |
chris | 0:752fc2753b90 | 44 | float SRF08::read() { |
chris | 0:752fc2753b90 | 45 | |
chris | 0:752fc2753b90 | 46 | char cmd[2]; |
chris | 0:752fc2753b90 | 47 | char echo[2]; |
chris | 0:752fc2753b90 | 48 | |
chris | 0:752fc2753b90 | 49 | |
chris | 0:752fc2753b90 | 50 | // Get range data from SRF08 |
chris | 0:752fc2753b90 | 51 | // Send Tx burst command over I2C bus |
chris | 0:752fc2753b90 | 52 | cmd[0] = 0x00; // Command register |
chris | 0:752fc2753b90 | 53 | cmd[1] = 0x51; // Ranging results in cm |
chris | 0:752fc2753b90 | 54 | m_i2c.write(m_addr, cmd, 2); // Send ranging burst |
chris | 0:752fc2753b90 | 55 | |
chris | 0:752fc2753b90 | 56 | wait(0.07); // Wait for return echo |
chris | 0:752fc2753b90 | 57 | |
chris | 0:752fc2753b90 | 58 | // Read back range over I2C bus |
chris | 0:752fc2753b90 | 59 | cmd[0] = 0x02; // Address of first echo |
chris | 0:752fc2753b90 | 60 | m_i2c.write(m_addr, cmd, 1, 1); // Send address of first echo |
chris | 0:752fc2753b90 | 61 | m_i2c.read(m_addr, echo, 2); // Read two-byte echo result |
chris | 0:752fc2753b90 | 62 | |
chris | 0:752fc2753b90 | 63 | // Generate PWM mark/space ratio from range data |
chris | 0:752fc2753b90 | 64 | float range = (echo[0]<<8)+echo[1]; |
chris | 0:752fc2753b90 | 65 | |
chris | 0:752fc2753b90 | 66 | return range; |
chris | 0:752fc2753b90 | 67 | } |