mirror of
https://github.com/mytechnotalent/Embedded-Hacking.git
synced 2026-05-16 21:23:33 +02:00
Kevin Thomas
108 lines
5.2 KiB
C
108 lines
5.2 KiB
C
/**
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* @file 0x0008_uninitialized-variables-e.c
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* @brief Blink LED using pure inline ARM assembly with direct register addresses
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* @author Kevin Thomas
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* @date 2025
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*
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* MIT License
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*
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* Copyright (c) 2025 Kevin Thomas
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*
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* -----------------------------------------------------------------------------
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*
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* Blinks an LED on GPIO16 using pure inline ARM assembly. No SDK calls, no
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* includes. Configures PADS_BANK0, IO_BANK0, and GPIO coprocessor via direct
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* register addresses and mcrr instructions, with a busy-wait delay loop.
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*
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* Wiring:
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* GPIO16 -> LED anode (with current-limiting resistor to GND)
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*/
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int main(void) {
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__asm__ volatile (
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// gpio_init(LED_PIN);
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/// gpio_set_dir(LED_PIN, GPIO_IN);
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//// gpioc_bit_oe_put(LED_PIN, GPIO_OUT);
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"movs r4, #0x10\n" // GPIO16
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"movs r5, #0x01\n" // bit 1; used for OUT/OE writes
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"mcrr p0, #4, r4, r5, c4\n" // gpioc_bit_oe_put(16, 1); p102
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// gpio_set_function(LED_PIN, GPIO_FUNC_SIO);
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/// hw_write_masked(&pads_bank0_hw->io[LED_PIN],
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/// PADS_BANK0_GPIO0_IE_BITS,
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/// PADS_BANK0_GPIO0_IE_BITS | PADS_BANK0_GPIO0_OD_BITS
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/// );
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//// hw_xor_bits(addr, (*addr ^ values) & write_mask);
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"ldr r3, =0x40038044\n" // &pads_bank0_hw->io[16]; p785, p796
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"ldr r2, [r3]\n" // load current config
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"bic r2, r2, #0x80\n" // clear OD; output disable
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"orr r2, r2, #0x40\n" // set IE; enable input buffer
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"str r2, [r3]\n" // store updated config
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/// io_bank0_hw->io[LED_PIN].ctrl = GPIO_FUNC_SIO << IO_BANK0_GPIO0_CTRL_FUNCSEL_LSB;
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"ldr r3, =0x40028084\n" // &io_bank0_hw->io[16].ctrl; p603, p637
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"ldr r2, [r3]\n" // load current config
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"bic r2, r2, #0x1f\n" // clear FUNCSEL bits [4:0]
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"orr r2, r2, #5\n" // set FUNCSEL = 5 (SIO)
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"str r2, [r3]\n" // store updated config
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/// hw_clear_bits(&pads_bank0_hw->io[gpio], PADS_BANK0_GPIO0_ISO_BITS);
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"ldr r3, =0x40038044\n" // &pads_bank0_hw->io[16]; p785, p796
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"ldr r2, [r3]\n" // load current config
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"bic r2, r2, #0x100\n" // clear ISO bit (bit 8) un‑isolate pad
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"str r2, [r3]\n" // store updated config
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// gpio_set_dir(LED_PIN, GPIO_OUT);
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/// gpioc_bit_oe_put(LED_PIN, GPIO_OUT);
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"movs r4, #0x10\n" // GPIO16
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"movs r5, #0x01\n" // bit 1; used for OUT/OE writes
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"mcrr p0, #4, r4, r5, c4\n" // gpioc_bit_oe_put(16, 1); p102
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// while (true)
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"1:\n" // loop start
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// gpio_put(LED_PIN, 1);
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/// gpioc_bit_out_put(LED_PIN, 1);
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"movs r4, #0x10\n" // GPIO16
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"movs r5, #0x01\n" // bit 1; used for OUT/OE writes
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"mcrr p0, #4, r4, r5, c0\n" // gpioc_bit_out_put(16, 1)
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// sleep_ms(500);
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/// sleep_us(500 * 1000ull);
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"ldr r2, =0x17D7840\n" // r2 = ~8.4M cycles
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"2:\n" // delay loop
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"subs r2, r2, #1\n" // decrement counter
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"bne 2b\n" // repeat until zero
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// gpio_put(LED_PIN, 1);
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/// gpioc_bit_out_put(LED_PIN, 1);
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"movs r4, #0x10\n" // GPIO16
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"movs r5, #0x00\n" // bit 0; used for OUT/OE writes
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"mcrr p0, #4, r4, r5, c0\n" // gpioc_bit_out_put(16, 0)
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// sleep_ms(500);
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/// sleep_us(500 * 1000ull);
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"ldr r2, =0x17D7840\n" // r2 = ~8.4M cycles
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"3:\n" // delay loop
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"subs r2, r2, #1\n" // decrement counter
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"bne 3b\n" // repeat until zero
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// jmp
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"b 1b\n" // repeat forever
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);
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}
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