Cellular AT-modem device model for ra8_emulator (attached to SCI7). More...

#include "board_periph_modem.h"
#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include "emu_host_io_internal.h"

Include dependency graph for board_periph_modem.c:

Data Structures
struct	modem_reply_t
	One scripted (command -> response) pair. More...
struct	modem_model_t
	The modelled modem's whole state. More...

Enumerations
enum	modem_geom_t : uint32_t { k_modem_channel = 7U , k_modem_cmd_cap = 64U , k_modem_resp_cap = 96U , k_modem_cr = 13U , k_modem_lf = 10U }
	Sizing constants for the modem line model (no magic numbers). More...

Functions
static RA8_INTERNAL uint32_t	internal_modem_emit (const char resp, uint8_t out, uint32_t out_cap)
	Copy a NUL-terminated response into `out`, bounded by `out_cap`.
static RA8_INTERNAL uint32_t	internal_modem_answer_line (uint8_t *out, uint32_t out_cap)
	Answer the completed command line in `s_modem.cmd`.
bool	board_modem_attach (void)
	Attach (arm) the modelled AT cellular modem.
bool	board_modem_attached (void)
	Report whether the AT modem model is currently attached.
uint8_t	board_modem_channel (void)
	SCI channel the modem is wired to (RXD7 / TXD7 = SCI7).
uint32_t	board_modem_feed_tx (uint8_t tx, uint8_t *out, uint32_t out_cap)
	Feed one firmware-transmitted byte into the modem and drain a reply.
void	board_modem_reset (void)
	Clear the modem's parser state (keeps the attached flag).
void	board_modem_report (void)
	Print a one-line end-of-run summary if the modem was exercised.

Variables
static const modem_reply_t	s_k_modem_script []
	The AT script the modelled modem answers.
static const char	s_k_modem_cme_error [] = "\r\n+CME ERROR: 4\r\n"
	Response for a command not present in s_k_modem_script.
static modem_model_t	s_modem
	The single modelled modem.

Detailed Description

Cellular AT-modem device model for ra8_emulator (attached to SCI7).

Implements board_periph_modem.h. The modem is a line state machine on the SCI7 UART: it accumulates the bytes the ra8_modem_at driver clocks out one at a time (each a TDR write the SCI_B block routes here), and when the terminating \r arrives it answers with the exact byte stream a real SIM7600 / BG95-class modem would send. The SCI_B block pushes that stream back into the channel's RX queue (RDR / RDRF), so the firmware's genuine polled ra8_sci_getc_polling path drains it exactly as on silicon (EIL == HIL for the AT protocol).

The AT script answered here mirrors the modem_at_demo example. An unrecognised command is rejected with +CME ERROR: 4 ("operation not supported") exactly as a modem with AT+CMEE=1 active would, so the demo's error branch is faithful. AT+CREG=1 (enable registration URCs) answers OK and then stages an unsolicited +CREG: 1 so the demo's URC dispatch fires, matching a modem reporting its current registration on enable.

Self-registers nothing with the peripheral core – it is a pure device model the SCI_B block calls into (attach / attached / channel / feed_tx / reset / report), the same shape as board_periph_sd.c and board_periph_eink.c.

Copyright: Copyright (c) 2026 Brighton Sikarskie SPDX-License-Identifier: MIT

Since: 0.1.0

Definition in file board_periph_modem.c.

Enumeration Type Documentation

◆ modem_geom_t

enum modem_geom_t : uint32_t

Sizing constants for the modem line model (no magic numbers).

Enumerator
k_modem_channel	RXD7/TXD7 = SCI7 (MikroBUS UART).
k_modem_cmd_cap	Longest AT command line accepted.
k_modem_resp_cap	Longest scripted response.
k_modem_cr	Carriage return (line terminator).
k_modem_lf	Line feed (dropped from the line).

Definition at line 43 of file board_periph_modem.c.

Function Documentation

◆ board_modem_attach()

bool board_modem_attach ( void )

Attach (arm) the modelled AT cellular modem.

Sets the module's armed flag so board_modem_attached returns true and the SCI_B block routes the modem channel's TDR writes into board_modem_feed_tx. Idempotent: a second call re-arms and clears the parser state.

Returns: true once the modem is armed and answering.

Return values

true	Modem armed (always, on this in-memory model).

Precondition: Called once during ra8_emulator start-up (single-threaded arg parse).; No physical hardware is required.

Postcondition: board_modem_attached returns true.; The command accumulator and response FIFO are empty.

Note: Not thread-safe; ra8_emulator is single-threaded.

Since: 0.1.0

Definition at line 150 of file board_periph_modem.c.

References board_modem_reset(), and s_modem.

Referenced by internal_args_try_mode().

◆ board_modem_attached()

bool board_modem_attached ( void )

Report whether the AT modem model is currently attached.

Returns: true if --modem armed the model.

Return values

false No --modem was passed.

Precondition: None.; None.

Postcondition: No state is modified.; No state is modified.

Note: Not thread-safe; ra8_emulator is single-threaded.

Since: 0.1.0

Report whether the at modem model is currently attached; this step is contained within the board periph modem model and uses bounded caller or module-owned storage.

Definition at line 157 of file board_periph_modem.c.

References s_modem.

Referenced by internal_sci_reg_write().

◆ board_modem_channel()

uint8_t board_modem_channel ( void )

SCI channel the modem is wired to (RXD7 / TXD7 = SCI7).

Matches k_ra8_board_mikrobus_uart_sci_channel on the firmware side so the SCI_B block routes only that channel's bytes into the model.

Returns: The modem's SCI channel number (7).

Return values

7	Always, for the EK-RA8D2 MikroBUS UART mapping.

Precondition: None.; None.

Postcondition: No state is modified.; No state is modified.

Since: 0.1.0

Note: The operation is synchronous and does not transfer heap ownership.

Definition at line 162 of file board_periph_modem.c.

References k_modem_channel.

Referenced by internal_sci_reg_write().

◆ board_modem_feed_tx()

uint32_t board_modem_feed_tx	(	uint8_t	tx,
		uint8_t *	out,
		uint32_t	out_cap )

Feed one firmware-transmitted byte into the modem and drain a reply.

Appends tx to the command-line accumulator. Most bytes buffer silently and return 0; the terminating \r closes the line, looks up the scripted response for that AT command, copies it into out (bounded by out_cap) and returns its length. An unrecognised command yields +CME ERROR: 4. A command whose response also stages an unsolicited +CREG URC (the AT+CREG=1 enable) appends that URC after the OK so the demo's ra8_modem_at_poll dispatch fires exactly as on silicon.

Parameters

[in]	tx	The byte the firmware wrote to the modem-channel TDR.
[out]	out	Destination for any response bytes (may stay untouched).
[in]	out_cap	Capacity of `out` in bytes.

Returns: Number of response bytes written to out (0 if none this byte).

Return values

0	The byte was buffered; no complete line yet.

Precondition: out is non-null and points to at least out_cap bytes.; The model is attached (callers guard with board_modem_attached).

Postcondition: On a completed line out holds a full modem response (<= out_cap).; The command accumulator is reset after a completed line.

Note: Not thread-safe; ra8_emulator is single-threaded.

Since: 0.1.0

Definition at line 167 of file board_periph_modem.c.

References internal_modem_answer_line(), k_modem_cmd_cap, k_modem_cr, k_modem_lf, and s_modem.

Referenced by internal_sci_reg_write().

◆ board_modem_report()

void board_modem_report ( void )

Print a one-line end-of-run summary if the modem was exercised.

Precondition: None.; None.

Postcondition: One line is written to injected error sink iff at least one command was answered.; No state is modified.

Since: 0.1.0

Print a one-line end-of-run summary if the modem was exercised; this step is contained within the board periph modem model and uses bounded caller or module-owned storage.

Note: The operation is synchronous and does not transfer heap ownership.

Definition at line 193 of file board_periph_modem.c.

References priv_emu_io_errf(), and s_modem.

Referenced by internal_sci_report().

◆ board_modem_reset()

void board_modem_reset ( void )

Clear the modem's parser state (keeps the attached flag).

Called from the SCI block reset so a mid-run reset re-frames the command accumulator without detaching the modem (the SCI reset re-frames transport, not the modem's presence). Run counters are retained for the end-of-run report.

Precondition: None.; None.

Postcondition: The command accumulator is empty; the attached flag is unchanged.; Run counters (commands answered, errors) are retained.

Since: 0.1.0

Note: The operation is synchronous and does not transfer heap ownership.

Definition at line 187 of file board_periph_modem.c.

References s_modem.

Referenced by board_modem_attach(), and internal_sci_reset().

◆ internal_modem_answer_line()

RA8_INTERNAL uint32_t internal_modem_answer_line	(	uint8_t *	out,
		uint32_t	out_cap )

static

Answer the completed command line in s_modem.cmd.

Parameters

[out]	out	Destination for the response bytes.
[in]	out_cap	Capacity of `out` in bytes.

Returns: Number of response bytes written.

Answer the completed command line in s_modem.cmd; this step is contained within the board periph modem model and uses bounded caller or module-owned storage.

Return values

value The operation-specific modem answer line value.

Precondition: Arguments satisfy the ranges documented for modem answer line.; The call executes on the emulator's single owning thread.

Postcondition: State changes remain confined to the board periph modem model and documented output objects.; Ownership of caller-supplied storage is unchanged.

Note: The operation is synchronous and does not transfer heap ownership.

Since: 0.1.0

Definition at line 136 of file board_periph_modem.c.

References internal_modem_emit(), RA8_INTERNAL, s_k_modem_cme_error, s_k_modem_script, s_modem, and strcmp().

Referenced by board_modem_feed_tx().

◆ internal_modem_emit()

RA8_INTERNAL uint32_t internal_modem_emit	(	const char *	resp,
		uint8_t *	out,
		uint32_t	out_cap )

static

Copy a NUL-terminated response into out, bounded by out_cap.

Parameters

[in]	resp	NUL-terminated response string.
[out]	out	Destination buffer.
[in]	out_cap	Capacity of `out` in bytes.

Returns: Number of bytes copied (<= out_cap).

Copy a nul-terminated response into out, bounded by out_cap; this step is contained within the board periph modem model and uses bounded caller or module-owned storage.

Return values

value The operation-specific modem emit value.

Precondition: Arguments satisfy the ranges documented for modem emit.; The call executes on the emulator's single owning thread.

Postcondition: State changes remain confined to the board periph modem model and documented output objects.; Ownership of caller-supplied storage is unchanged.

Note: The operation is synchronous and does not transfer heap ownership.

Since: 0.1.0

Definition at line 113 of file board_periph_modem.c.

References RA8_INTERNAL.

Referenced by internal_modem_answer_line().

Variable Documentation

◆ s_k_modem_cme_error

const char s_k_modem_cme_error[] = "\r\n+CME ERROR: 4\r\n"

static

Response for a command not present in s_k_modem_script.

Definition at line 82 of file board_periph_modem.c.

Referenced by internal_modem_answer_line().

◆ s_k_modem_script

const modem_reply_t s_k_modem_script[]

static

Initial value:

                                            = {
  {"AT", "\r\nOK\r\n"},
  {"ATE0", "\r\nOK\r\n"},
  {"AT+CMEE=1", "\r\nOK\r\n"},
  {"AT+CPIN?", "\r\n+CPIN: READY\r\n\r\nOK\r\n"},
  {"AT+CSQ", "\r\n+CSQ: 17,99\r\n\r\nOK\r\n"},
  {"AT+CREG=1", "\r\nOK\r\n\r\n+CREG: 1\r\n"},
  {"AT+CREG?", "\r\n+CREG: 1,1\r\n\r\nOK\r\n"},
  {"AT+CGATT?", "\r\n+CGATT: 1\r\n\r\nOK\r\n"},
}

The AT script the modelled modem answers.

Responses are framed the way a real modem frames them: a leading \r\n, the payload line(s), a blank line, then the final OK. AT+CREG=1 additionally stages an unsolicited +CREG: 1 after its OK (the modem reporting current registration once URCs are enabled). Any command not in this table falls through to +CME ERROR: 4.

Definition at line 70 of file board_periph_modem.c.

Referenced by internal_modem_answer_line().

◆ s_modem

modem_model_t s_modem

static

The single modelled modem.

Definition at line 97 of file board_periph_modem.c.

Referenced by board_modem_attach(), board_modem_attached(), board_modem_feed_tx(), board_modem_report(), board_modem_reset(), and internal_modem_answer_line().

Data Structures

Enumerations

Functions

Variables

Detailed Description

Enumeration Type Documentation

◆ modem_geom_t

Function Documentation

◆ board_modem_attach()

◆ board_modem_attached()

◆ board_modem_channel()

◆ board_modem_feed_tx()

◆ board_modem_report()

◆ board_modem_reset()

◆ internal_modem_answer_line()

◆ internal_modem_emit()

Variable Documentation

◆ s_k_modem_cme_error

◆ s_k_modem_script

◆ s_modem