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sinclairrf |
; Copyright 2014, Sinclair R.F., Inc.
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;
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; Notes:
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; - This uses a simple board with 5 on/off switches connected to the TCA9554
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; on pins P0, P1, P2, P4, and P5 and with an LED connected to P3. The 3
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; address pins are held to ground by pull-down resistors.
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; - run in 400 kHz mode
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.constant I2C_WR_ADDR 0x40
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.constant I2C_RD_ADDR 0x41
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.constant I2C_INPUT 0x00
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.constant I2C_OUTPUT 0x01
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.constant I2C_INVERT 0x02
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.constant I2C_CONFIG 0x03
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.include char.s
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.include ../../lib_i2c.s
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.main
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N"\r\nUC Started\r\n" .call(uart_tx)
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; Configure P3 as an output. Hang if a NACK is received.
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; Note: bit=0 ==> output, bit=1 ==> input.
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.call(i2c_send_start)
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.call(i2c_send_byte,I2C_WR_ADDR)
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.call(i2c_send_byte,I2C_CONFIG) or
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.call(i2c_send_byte,0xF7) or
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.call(i2c_send_stop)
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.jumpc(hang)
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; Configure P3 with a low signal to turn on the LED. Hang if a NACK is received.
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.call(i2c_send_start)
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.call(i2c_send_byte,I2C_WR_ADDR)
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.call(i2c_send_byte,I2C_OUTPUT) or
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.call(i2c_send_byte,0xF7) or
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.call(i2c_send_stop)
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.jumpc(hang)
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; Push the current state onto the data stack.
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.call(read_state)
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:infinite
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; Wait for the interrupt.
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; Note: This is disabled because the interrupt line either goes low for a
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; long time or goes low for a very short time. The observed behavior
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; is not consistent with the data sheet.
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; :wait_for_interrupt .inport(I_INT) 0= .jumpc(wait_for_interrupt)
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; Read the device state until it changes and then display the new value.
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:wait_change .call(read_state) swap over - 0= .jumpc(wait_change)
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>r N"\r\n" r@ .call(char__byte_to_2hex) .call(uart_tx) r>
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.jump(infinite)
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; Error stack for NACK failure.
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:hang
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N"NACK received\r\n" .call(uart_tx)
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:in_hang .jump(in_hang)
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;
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; Read the switch settings.
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;
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; ( - u )
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.function read_state
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.call(i2c_send_start)
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.call(i2c_send_byte,I2C_WR_ADDR) drop
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.call(i2c_send_byte,I2C_INPUT) drop
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.call(i2c_send_restart)
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.call(i2c_send_byte,I2C_RD_ADDR) drop
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.call(i2c_read_byte,1)
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.return
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;
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; Output the null terminated string on the data stack.
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;
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; ( '\0' u ... u - )
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.function uart_tx
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:loop
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; Wait for the UART to not be busy (there is no output FIFO).
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.inport(I_UART_TX_BUSY) .jumpc(loop)
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; Send the next character
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.outport(O_UART_TX)
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; Continue the loop if the next character is not the null character.
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.jumpc(loop,nop)
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; Return and drop the terminating null character.
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.return(drop)
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