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Reject unsupported color schemes at direct-write START #3

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Reject unsupported color schemes at direct-write START #3

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13 changes: 13 additions & 0 deletions EPD/EPD_service.c
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Original file line number Diff line number Diff line change
Expand Up @@ -397,6 +397,19 @@ static void handle_direct_write_start(ble_epd_t* p_epd, uint8_t* data, uint16_t
send_error_response(p_epd, RESP_DIRECT_WRITE_ERROR);
return;
}
// nRF only renders BW (color_scheme 0) and BWR (color_scheme 1). For any
// other scheme the client streams data whose size this firmware cannot
// compute, so it would over/under-run RAM and refresh garbage while still
// ACKing success. Reject unsupported schemes up front instead of powering
// the panel. Reply with the standard 4-byte NACK frame
// {0xFF, cmd, error, 0x00} so the client fails fast.
if (p_epd->display_config == NULL || p_epd->display_config->color_scheme > 1) {
NRF_LOG_WARNING("DW: unsupported color_scheme; sending NACK");
uint8_t nack[] = {0xFF, (uint8_t)(CMD_DIRECT_WRITE_START & 0xFF),
RESP_ERR_UNSUPPORTED_SCHEME, 0x00};
(void)send_response(p_epd, nack, sizeof(nack));
return;
}
if (directWriteState.active) {
cleanup_direct_write_state(p_epd);
}
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1 change: 1 addition & 0 deletions EPD/EPD_service.h
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Expand Up @@ -101,6 +101,7 @@ void ble_epd_evt_handler(ble_evt_t const* p_ble_evt, void* p_context);
#define RESP_DIRECT_WRITE_REFRESH_SUCCESS 0x73
#define RESP_DIRECT_WRITE_REFRESH_TIMEOUT 0x74
#define RESP_DIRECT_WRITE_ERROR 0xFF
#define RESP_ERR_UNSUPPORTED_SCHEME 0x02 // NACK error code for color schemes this firmware cannot render
#define RESP_LED_ACTIVATE_ACK 0x73
#define RESP_FIRMWARE_VERSION 0x43
#define RESP_MSD_READ 0x44
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