Clavier

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Everything posted by Clavier

  1. The delay() function is part of the official Arduino API. It is implemented with a busy loop, based on the CPU clock. The sleep() function is not part of the official Arduino API. It powers down the CPU, and measures time based on the VLO, which doesn't have a accurately specified frequency to begin with and has much higher temperature and voltage coefficients than other clock sources.
  2. The variables i2 and i22 are normal variables (in RAM), and are automatically reinitialized whenever the device resets. The only place where you read from the flash is in the blink1() function. To get the values from the flash, you must read from the flash at the beginning of the program.
  3. Section 8.2.4 of the User's Guide says:
  4. Please see table 9 of the LIS3DH datasheet; you are not allowed to apply voltages greater than 0.3 V to the SDA/SCL pins when VACC = 0 V. You must disconnect these signals before powering down the chip. (And when it's powered down, ACC_INT1 might be floating; you have to deal with that.) I'd guess VACC gets powered through R8/R9, or through the chip's ESD protection diodes (which go from any I/O to VDD).
  5. With SMCLK running at about 1 MHz, and a divider of 1 = WDTIS__128M, the expiration should happen after about 134 seconds. Anyway, Energia uses the watchdog interval timer interrupt to implement micros() and delay().
  6. The G2553 chip itself does not have USB support. You can go through the LaunchPad's "application"/"backchannel" UART; you firmware then just needs to write/read the UART. You also need an application on the host PC to read from one COM port and write to another. But why use USB? Why can't you control the solenoid directly from the LaunchPad?
  7. In theory, the function call overhead should have taken care of the one-cycle delay. It appears that in practice, the compiler managed to optimize that away somehow. (I guess your MAP_ functions do not go to ROM but to your own copy of driverlib, and the compiler inlined all of it.)
  8. This sounds like a hardware bug. Can you reproduce it with a program that uses neither Energia nor driverlib?
  9. https://github.com/energia/Energia and https://github.com/energia/msp430-lg-core But the latest release there is 1.6.8.
  10. Clavier's Short Guide to I²C Slaves on the MSP430x2xx Family Read section 17.3.4.1 of the User's Guide, and the example code. Slave mode is somewhat easier than master mode because you do not have to care about getting the transaction sequence correct; you just react to the master's requests. The slave address is an arbitrary but unique 7-bit number. Just put it into the I2COA ("own address") register; the USCI module will automatically handle transactions to this address. You do not need to configure a clock source; the clock signal is supplied by the master. When the master has written a byte, you get an RXIFG interrupt. Your interrupt handler must read that byte from RXBUF. (You can set the TXNACK bit after reading RXBUF, this will tell the master to stop after the following byte.) When the master wants to read a byte, you get a TXIFG interrupt. Your interrupt handler must write a byte to TXBUF. If your code is slow, the USCI module will automatically stop the bus via clock stretching until you have reacted. You can get notifications when start and stop conditions happen (STTIFG and STPIFG), but that is not always necessary. The I²C protocol itself defines only byte reads and writes. If you have registers, you have to handle the register address yourself. Typically, the first write after a start condition is the register address, and all following writes (and all reads) are from/to the specified register (and often the register address automatically increments). As a slave, you have no control over what the master does; you must react to any write and read requests at any time. (If you really have nothing to read, just send the last byte again, or some garbage byte.)
  11. This is how I do my GPIO initialization. It doesn't handle any later GPIO accesses, but it's a nice table, and smaller and faster than configuring the bits one by one. /* use 0 or 1 to set the output level */ #define OUTPUT 0x00 /* default */ #define INPUT 0x02 #define PULL_DOWN 0x04 #define PULL_UP 0x05 #define REDUCED_DRIVE 0x00 /* default */ #define FULL_DRIVE 0x08 #define GPIO 0x00 /* default */ #define PERIPHERAL 0x10 struct digital_io_init_f5529 { u8 P1[8]; u8 P2[8]; u8 P3[8]; u8 P4[8]; u8 P5[8]; u8 P6[8]; u8 P7[8]; u8 P8[3]; u8 PJ[4]; }; static void init_port(const u8 *init, unsigned int count, uint16_t int base_address) { uint16_t out = 0, dir = 0, ren = 0, ds = 0, sel = 0; uint16_t bit; for (bit = 1; count > 0; init++, bit <<= 1, count--) { if (*init & 1) out |= bit; if (!(*init & INPUT)) dir |= bit; if (*init & PULL_DOWN) ren |= bit; if (*init & FULL_DRIVE) ds |= bit; if (*init & PERIPHERAL) sel |= bit; } HWREG16(base_address + OFS_PAOUT) = out; HWREG16(base_address + OFS_PADIR) = dir; HWREG16(base_address + OFS_PAREN) = ren; HWREG16(base_address + OFS_PADS ) = ds; HWREG16(base_address + OFS_PASEL) = sel; } static void init_ports(const struct digital_io_init_f5529 *init) { init_port(init->P1, 8 + 8, PA_BASE); init_port(init->P3, 8 + 8, PB_BASE); init_port(init->P5, 8 + 8, PC_BASE); init_port(init->P7, 8 + 3, PD_BASE); init_port(init->PJ, 4, PJ_BASE); } void init() { init_ports(&(const struct digital_io_init_f5529){ .P4[4] = PERIPHERAL | OUTPUT, .P4[5] = PERIPHERAL | INPUT, .P7[0] = GPIO | INPUT | PULL_UP, .P7[1] = GPIO | OUTPUT | FULL_DRIVE, /* ... */ }); }
  12. If the Energia libraries do not have support fo the SD16 module, then your only choice is to program the registers directly. Which is what these examples show.
  13. There is a "MSP430F20x3 Code Examples" package on TI's web site
  14. You do not need to add code. The documentation for endTransmission() says: // Originally, 'endTransmission' was an f(void) function. // It has been modified to take one parameter indicating // whether or not a STOP should be performed on the bus. // Calling endTransmission(false) allows a sketch to // perform a repeated start.
  15. Huh? All MSP430 comparator modules are able to raise an interrupt for this.
  16. Many MSP430 models have a comparator. You can find out whether this is the case for your specific model (whatever it is) by looking into the datasheet.
  17. Already answered on E2E.
  18. If you have configured the compiler correctly, i.e., for the G2231, these two headers have exactly the same effect.
  19. Toggling the PxIES bit once has a race condition, when the signal switches again before the interrupt has run. You also have to check the current state of the PxIN bit to ensure that PxIES catches the next edge. But the easiest way to get interrupts for both edges is to route the signal to two pins.
  20. There is no flyback diode in this device. All MOSFETS have a parasitic body diode, but it is no help for you because it is across the source/drain channel, not across the relay. The NXP's BSS138 model has ESD diodes that protect the gate insulation, but again, these does not help you. You cannot avoid putting a separate diode across the relay.
  21. The 2N7000 would require 5 V to switch on completely, so it is not suitable for the Tiva. Why do you want to avoid the flyback diode? This would require a high-voltage transistor, and those typically have higher gate threshold voltages.
  22. P1.6 is interrupt capable. If your GPIO interrupt does not work, then your code did somewthing wrong.
  23. You can read out the memory with the debugger, but unless you have some unique string in there, it would be hard to know which program it is. You can use whatever partitioning scheme you like, but you have to implement it yourself.
  24. In theory, begin() should never set the output low. In practice, it is implemented like this:
  25. The User's Guide says: When using Energia, call flush(), set UCTXBRK, and write() a 0 byte. (How long must the break be? Longer than what the G2553 sends?) begin() is needed to connect the UART to the pin. (end() is needed only if you want to use the pin as GPIO later.) begin() does not yet send any data, so the output is in the idle state (high).